清理焊渣时必须戴上(),并避免对着人的敲打焊渣。
A.面罩
B.有色眼镜
C.白光眼镜
参考答案:C
Much to my _____, the student has come to realize the importance of honesty.
A.horror
B.relief
C.sorrow
D.curiosity
渣沟堵塞的原因?