双晶片联合探头，由于盲区较小，因此有利于近表面缺陷的探测。
参考答案：对
The first textbooks written for teaching English as a foreign language _____ in the 16th century. [ ]
A. came about
B. came out
C. came along
D. came up
GPS是（）的缩写。
A、全球卫星定位系统
B、全球监测系统
C、全球导航系统
