Being examined twice a year, whether it is a car or a bus or a truck, it is the rule that every driver____ obey in this city.

--It is really fun to hike and I often go hiking in the forest.--But hiking alone in the forest ______ be very dangerous.

One of the National Health Regulations is that public schools ______ actively create conditions for sports facilities opened to the public.

-There is someone knocking at the door.- It ______ be Jimmy, he has gone to ShangHai .

—I hear you’ve got a new iPhone 4S. ______ I have a look?—Yes, certainly.