derly need special care in winter, as they are______ to the sudden change of weather.

The bikes produced in that factory are of highquality So they ______ well both at home and abroad

It is often recommended that children _______ chances to get close to nature.

It’s the office！So you ________ know eating is not allowed here.—Oh，sorry.

It seems that Mr. Wu is standing there.— It ______ be him because he called me from Canadajust now.