—It’s said that John will be in a job paying over $60,000 ______ year.

—Right, he will also get paid by ______ week.

A．a; the

B．the; the

C．the; a

D．a; a

微生物先分泌胞外酶将半纤维素水解为（）后，才能用于细胞呼吸代谢作用。