Take a hat with you in case the sun is very hot.

A．in case

B．so that

C．in order that

D．when

酸性焊条用得比较广泛的原因之一是（）

A.焊接质量好

B.焊缝抗裂性好

C.焊接工艺性能较好

D.焊缝含氢量少