Instead of staying the same every day,Mary’s working hours are .

I don’t know when he _____. When he _____ here, I’ll call you in a minute.

Many trees ____ along the streets every year. So the air is very fresh now.

Things made by hand are usually more expensive than _ produced in factories.

ma paid a visit to China in November, 2009,_______, needless to say, must strengthen the Sino-US ties