涡静脉收集（）
A.视网膜的血液
B.巩膜的血液
C.全部葡萄膜的血液
D.部分虹膜睫状体和全部脉络膜的血液
E.虹膜睫状体和巩膜的血液
参考答案：D
19．We were that the Wenchuan earthquake left the whole city in ruins.
A．shocked
B．worried about
C．worrying
D．Shocking\]
单子叶植物茎的构造有哪些特点？
