泌尿系男生殖系肿瘤中哪个器官最常见（）。
A.肾脏
B.膀胱
C.输尿管
D.睾丸
E.前列腺
参考答案：B
滤料酸洗合格后，放掉酸溶液，用（）左右的清水进行清洗，直到水质合格为止。
A、20℃
B、30℃
C、40℃
D、50℃
She worked so quietly ______ no one knew she was there. [ ]
A. which
B. after
C. as
D. that
