-----They used to be good friends, but now they are like strangers. ----- How _____ this ______?
A. were; come about B. did; come about
C. were; taken place D. were; happened
This new-type machine____________ little room.
A. takes up B. is taken up C. has been taken up D. is taking up
The cattle _______ grazing on the grass.
A. were B. was C. be D. is
Such a problem is＿＿＿＿difficult for a primary school student ＿＿＿.
A. so； to work B. very too； to work out
C. rather too； to work out D. quite too； to answer
— What does the sign over there read?
—“No person __________ smoke or carry a lighted cigarette，cigar or pipe in this area.”
A. will B. may
C. shall D. must
The best times to visit Shangri-la are spring and autumn ____ the temperature is at its mildest.
A. when B. where C. that D. which
