对低碳钢、中碳钢和低合金钢材质受力复杂的结构件进行焊接，其焊条的选用原则为（）。
A. 焊条强度一母材强度相等
B. 焊条强度比母材强度低一级
C. 焊条强度比母材强度高一级
D. 焊条化学成分与母材相同
Either of you ______ able to move that stone.
A. are
B. is
C. have been
D. be
Which one is NOT true in the following sentences
A. May is the best festival month in the Philippine.
B. In May, people will celebrate the festival during the whole month.
C. The last night of May is one of the heaviest nights of the year.
D. Filipino variation is a bamboo frame from which dangle packages of sweets fruit, and toys on strings.
下列疾病转归中，正确的是
A. 胞阻→胎动不安
B. 胎动不安→堕胎
C. 子晕→子痫
D. 异位妊娠→癥瘕
E. 以上都是
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