阻塞性黄疸时尿中胆红素（）
A.阴性
B.正常
C.减少
D.增加
E.不定
参考答案：D
—What do you think has caused his heart attack?
—It is ______.
A．because of his overweight
B．due to his being overweight
C．his being overweight
D．he is so overweight
一个刚片在平面内有（）个自由度。
A.1
B.2
C.3
D.4
