题干
Have you seen my dog? I _________ for it and still haven’t found it.
A：looked
B：was looking
C：have been looking
D：had been looking
答案(点此获取答案解析）
C
A：looked
B：was looking
C：have been looking
D：had been looking
合金随Cr含量变化的腐蚀性实验结果，下列有关说法正确的是