在选择钢丝绳的安全系数时,应按以下原则()选用。
A.与重物的质量相等;
B.安全、经济;
C.经济;
D.安全。
参考答案:B
The food ________ because it _________ good.
A. sold out soon; was tasted
B. was soon sold out; tasted
C. has soon sold out; tasted
D. will soon sold out; tasted
母亲妊娠晚期患急性乙型肝炎时,胎儿感染率为
A.25%B.50%C.70%D.85.90%E.100%