对粉末冶金制品或石墨制品进行渗透探伤时，应选用（）渗透液
参考答案：过滤性微粒
岩层厚度
Immediately after abandoning a vessel，lookouts should be posted aboard liferafts to look for（）.
A.survivors in the water
B.food and water
C.land
D.bad weather
