在地基比较差的地区修建拱桥，最好修建（）
A.空腹式拱
B.无铰拱
C.两铰拱
D.三铰拱
参考答案：B
—Would you like to play basketball with us this afternoon? — I have to study for tomorrow's test.
A．I'd love to
B．I'm afraid not
C．Sounds good
D．No problem
