焊缝系数是焊缝强度与母材强度之比,它小于或等于()
A.2.5
B.2
C.1.5
D.1
参考答案:D
下列属于青春期正常心理表现的是[ ]
①独立感增强
②有时会出现反复无常的情绪
③渴望得到别人的关注
④情绪复杂却稳定
A.②③④
B.①②④
C.①③④
D.①②③
The sixyearold girl infected with the H7N9 bird flu is in a ________ condition after receiving treatment.
A.stable
B.temporary
C.thoughtless
D.sensitive