选用低合金焊条时,可根据母材的化学成分及力学性能来考虑。( )
参考答案:错
His parents tried to _____ him to go abroad after his graduation from the university, but they failed. [ ]
A. persuade
B. advise
C. suggest
D. allow
Lucy and Lily ______ my sisters. [ ]
A. aren't
B. isn't
C. is
D. not