act up (no object): misbehave (for people); not work properly (for machines).
[blockquote]\"The babysitter had a difficult time. The children acted up all evening.\"
\"I guess I'd better take my car to the garage. It's been acting up lately.\"
[/blockquote]act like (inseparable): behave in a way that's like _____ .
[blockquote]\"What's wrong with Bob? He's acting like an idiot.\"
[blockquote]Note: This phrasal verb is very informal.
[/blockquote][/blockquote]add up (1. no object): logically fit together.
[blockquote]\"His theory is hard to believe, but his research adds up.\"
[blockquote]Note: This phrasal verb is often negative.
[/blockquote]\"His theory seems, at first, to be plausible, but the facts in his research don't add up.\"
[/blockquote]add up (2. separable): find the total.
[blockquote]\"What's the total of those bills? Could you add them up and see?\"
[/blockquote]add up to (inseparable): to total.
[blockquote]\"The bills add up to $734.96. That's more than I expected!\"
[/blockquote]ask out (separable): ask for a date.
[blockquote]\"Nancy has a new boy friend. Joe asked her out last night.\"