切除胸腺的新生动物,淋巴结内缺乏的细胞是()
A.B淋巴细胞
B.T淋巴细胞
C.巨噬细胞
D.K细胞
E.NK细胞
参考答案:B
When I______ the cinema, the film ______.
A.arrived at; began
B.got; began
C.got to; had begun
D.had got; had begun
为什么小型制氧机原先采用活塞式膨胀机,而大型制氧机均采用透平膨胀机?