犊牛去角为了便于牛成年后的管理,减少人畜伤害,去角的最佳时间为出生后( ) d,此时去角对犊牛造成的应激最小。
A. 3~7
B. 7~14
C. 14~28
D. 28~56
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A survey suggests that some people have difficulty ______ to write.
A. to learn
B. learning
C. learn
D. learnt
It was in their company ______ we met and discussed the issue.
A. that
B. which
C.how
D. what
The decision about such a big railway project can not be made ______ each member of the board agrees.
A.if
B. unless
C. though
D. as
There was no proof to show that this young man had committed thecrime,______ he was set free.
A. But
B. for
C. or
D. so