Most research in this field ____ by the Russians.
A. has carry out
B. have carried out
C. has been carried out
D. have been carried out
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All the surprises and gifts come from those who ____ you.
A. is to love
B. loved
C. loves
D. love
The pair of glasses ____him.
A. fit
B. is fit
C. fits
D. are fit
磁铁的两端磁性( )。
A. 最强
B. 最弱
C. 与中部一样
磁力线线条稀疏处表示磁场( )。
A. 强
B. 弱
C. 变强