对于肺癌的转移,下列哪个描述不正确
A.转移较快、较多见B.淋巴道转移首先至颈部淋巴结C.血道转移常见于脑D.早期肺癌无淋巴结转移
参考答案:B
如图所示,甲、乙两个门窗紧闭的房间里各有一位同学,乙房间的玻璃是双层的,中间抽成真空。
(1)甲、乙两个房间的同学都能看见树上的小鸟,这是为什么?
(2)但乙房间的同学听不到小鸟的“歌唱”,又是为什么?
41. If it ______ for the fence, he ______ into the river.
A. were not; fallen B. had not been; could have fallen
C were not; could fall D. had not been; could fall