新生儿持续性肺动脉高压的病因描述，正确的是（）
A.早产或低出生体重
B.肺血管发育不良
C.新生儿贫血
D.存在先天性心脏病
E.气胸
参考答案：B
When the teacher came in, he saw some boys _______ behind Daniel, _______ the computer games.
A．sit, watching
B．sitting, watching
C．sit, to watch
D．sitting, watched
要约的撤回
