How long have you been running ? —Since ______ .

US president Obama went to visit the Great Wall last November.—___________.[ ]

Why are you in such a hurry,Li Ping ? —-There____a basketball match between Class One and our class in five minutes.

The white shoes are nice. Can I _______?—Sure.

Do you have enough students to clean the laboratory? –No, I think we need____________ students.