后制动器的齿轮油应()天更换一次。
A、20
B、15
C、30
参考答案:A
需要降低胸部摄影条件的情况是()
A.大量胸腔积液
B.肺炎
C.肺气肿
D.肺纤维化
E.肺结核
He gave me two answers ______ the question, but ______ of them is right. [A] of, neither [B] to, both[C] to, neither