Scientists are convincedthepositive effect of laughter_____physical and mental health.

The thief was caught by the police in therailway station before he was able to _____.

He is different ______ his brother , but he is similar ______ his father.

Where do you think ______ he ______ the computer?　— SorryI have no idea

___________ many times, but he still couldn’t understand it.