再生器内上半段稀相区的气体流速的下限是为了防止()。
A.烟气夹带催化剂量过大
B.气体在稀相区停留时间过长
C.稀相催化剂跑损
D.碳堆积的发生
参考答案:B
—I didn’t go to work yesterday because my car broke down.
—You _______ mine.I wasn’t using it then.
A.might borrow
B.could have borrowed
C.must have borrowed
D.ought to borrow
二尖瓣狭窄患者叩诊心界为()
A.靴形心
B.梨形心
C.普大型心
D.心界向右侧移位
E.烧瓶样心