脱水器沉砂严重时,需要酸洗垢物,先用()%酸洗垢,反应停后用水冲洗。
A、20
B、30
C、50
D、70
参考答案:C
下面的()是中国佛教四大名山之一。
A.峨嵋山
B.青城山
C.黄山
D.泰山
---Why isn't he in the hospital with his injured mother?
---No one ______ him of the accident.
A.informed
B.informs
C.had informed
D.has informed