胸腺的作用是
A．T细胞发生场所B．B细胞定居场所C．T细胞成熟、分化场所D．B细胞产生免疫应答的场所E．T细胞定居场所
参考答案：C
The athlete fell off his bike when he _____ down the hill. [ ]
A. cycled
B. was cycling
C. had cycled
D. is cycling
（），字惟度，福清人，诗多反映兵乱和哀叹人民生活困苦，充满隐逸情调，著有《枕江堂集》。
A.陈常夏
B.谢亦骥
C.林佶
D.魏宪
