肽链合成后的加工主要的形式有（）。
A. 肽链N-端的切除。
B. 个别氨基酸的化学修饰。
C. 肽段的切除。
D. 亚基聚合和辅基的连接。
E. 肽链的形成。
A producer is someone who is generally ______ the preparation of a film but doesn’t direct the actors.
A. take charge of
B. be responsible for
C. in defiance of
D. in charge of
He could create ______ that have meaning ______ the time and places of his plays.
A. character; beyond
B. characters; beyond
C. characteristic; on
D. persons; in
______ the approach of Christmas, the weather turned cold.
A. For
B. At
C. On
D. With
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