He was busy writing the exam paper, only ___once in a while to check the time.

The climate here is always hot, summer and winter ______.

With the help of high technology, in the past few years, electronic business __________to bank industry, travel industry

Excuse me， Maria. Can I use your bike—Sure. Here you are. But you must return it _____ time.

Time ______, I’ll arrange for you to meet Professor Libefore you leave for Japan.