— _______ you got to know my telephone number?

— Through a friend of yours.

A．How was it

B．How was it that

C．Was it how that

D．How did

LD所属的酶种类是（）

A.氧化还原酶类

B.转移酶类

C.水解酶类

D.裂解酶类

E.异构酶类