水泵填料接头要互相错开()。
A.45°~90°
B.90°~120°
C.150°~240°
参考答案:B
The parents were unsettled for the first few days, _____ about their son's safety. [ ]
A. having worried
B. to worry
C. being worried
D. worried
产品防护系指()
A.产品在贮存时的防护活动
B.成品在交付过程中的防护活动
C.成品在交付过程中的防护活动
D.从原材料进厂到成品交付全过程的防护活动