选择括号内恰当的单词或词组填入空白处,使句意完整正确.We should try to smile ___________ (at/to) life.
Don’t cross the street _____________ (after/until) the traffic light turn green.
I couldn’t sleep as well as ___________ (usual/usually).
I am looking forward to ________ (hear/hearing) from you .
We’d like to book ten hard ____________ (sleep/sleeper) tickets.