is unpleasant, _____ whenyou are trying to sleep

You have no idea what I’ve had to ______ in finding the proper job in the last few months.

Alice promised me to come round to keep you company today.—But she ________I’ve been alone all day

It’s smoggy（多雾的） these days in Beijing city. That’s terrible!—– Yes, I hope to plant trees.________ trees, ______air pollution.

Charles Babbage is generally considered ______ thefirst computer.