slow down:  The police roadblock had slowed down traffic to a big snarl-up. (To make or become slower)
slow down:  I think you should slow down when you approach a bend. (To reduce speed of a vehicle)
slow down:  We had to slow down as the path began to zigzag steeply uphill. (To reduce one’s speed)

snap off:  She stopped reading, snapped off the light and closed her eyes to sleep. (To turn off a light)

snap on:  She snapped on the light when she entered the bedroom. (To turn on a light)
snap out of:  It’s unlike you to be so irritable; I wish you would snap out of it. (To get out of a bad mood) 
snap up: Hordes of customers snapped up the bargains that were on offer. (To quickly acquire something because it is cheap or in short supply)

speak of:  His belief that the law did not apply to him spoke of arrogance. (To indicate something exists) 

speak of:  I have to take this lowly job as I have no paper qualifications – none to speak of. (To indicate something is real) 

speak out:  The students spoke out against fraud and mismanagement in the university. (To voice protest about an issue) 

speak to:  The supervisor wants to speak to the two workers who fought in the canteen. (To talk to someone who has committed a wrong)

speak up:  You are asking me to speak up when I am shouting into the phone. (To speak loudly)

speak up:  Those at the back will have to speak up. (To speak loudly)
speak up:  If you feel so strongly about it, you can speak up at the next meeting. (To speak without fear)

stamp out:  The new government is determined to stamp out corruption. (To forcibly put an end to something)

stamp out:  He stamped out the dying flame. (To put out)

stand against:  Her daughter will be standing against her in the parliamentary election. (To be a candidate in an election)

stand around:  The crowd just stood around waiting for the ambulance to arrive. (To stand somewhere and do nothing)
stand aside:  He decided to stand aside and let a younger person take over. (To give up one’s position) 

stand by:  There is only one ambulance standing by at this moment. (To be ready for action if needed)

stand by:  She stood by what she said and would not retract her statement. (To maintain one’s attitude towards an issue)
stand by:  How could the world stand by and let this country go through a prolonged civil war. (To not get involved)
stand by:  Family members and friends stood by him throughout his trial. (To remain loyal to or supportive of someone)
stand by:  The collective decision has been made and every member has to stand by it. (To support and defend)

stand down:  The witness stood down after giving oral testimony about the murder. (To leave the witness box) 

stand down:  He stepped down as Managing Director in favour of his eldest son. (To resign)

stand for:  He is not going to stand for her personal insults much longer. (To put up with)

stand for:  Many people know what ‘IOU’ stands for ‘I owe you’. (To represent)
stand for:  We have yet to know what the newly-formed party stands for. (To publicly support a particular cause or policy)

stand in:  His two assistants stand in for him when he’s on a foreign assignment. (To act as a substitute) 

stand out:  Your dyed orange hair will certainly make you stand out in any crowd. (To be easily noticeable)

stand out:  Among the applicants, Julia stood out from the rest as the most qualified. (To be clearly better or the best)
stand out against:  The local people are standing out against the dumping of toxic waste. (To continue opposing or supporting something)

stand up:  He looks taller if he stands up straight. (To stand on one’s feet)

stand up:  The defence believed the charges were fabricated and would not stand up in court. (To stay valid)
stand up for:  You should stand up for your rights as citizens of this country. (To do something in defence of)
stand up to:  He wouldn’t dare stand up to his female boss even though he knew he was right. (To strongly defend against)
stand up to:  Can the boat that we built stand up to every weather condition at sea? (To remain undamaged or unaffected by)

start off:  His father started him off as a management trainee in his company. (To begin doing something)

start off:  He started it off by giving a brief account of how he became a public speaker. (To begin by doing something)
start off:  We have to start off early in order to arrive there before dusk. (To set forth)

start on:  The first coat of paint has thoroughly dried; we can now start on the top coat. (To begin to deal with something)

start on at:  She started on at me for not helping but only helping to eat. (To talk in a critical way)

start out:  He started out as a lance corporal but now he is a sergeant. (To begin one’s working life)

start over:  Your summary is full of mistakes; I’ll start over with you. (To redo from the beginning) 

start up:  I think we have to start up a different business; this one is failing. (To start an undertaking) 

start up:  The residents are starting up a vigilante group to patrol the neighbourhood. (To organize something) 
start up:  We had to call in the serviceman as the machine wouldn’t start up this morning. (To become operational)