—How old was Langlang?
—He was born ______ May 1st,1982. [ ]
A. in
B. at
C. on
D. for
答案:C
人在幼年时由于缺乏某种激素而导致侏儒症,这种激素是()
A.生长激素
B.甲状腺激素
C.糖皮质激素
D.肾上腺素
E.胰岛素
简答光电式转速与曲轴位置传感器的组成与工作原理。