若事务T对数据R已经加了X锁，则其他事务对数据R

A． 可以加S锁不能加X锁

B． 不能加S锁可以加X锁

C． 可以加S锁也可以加X锁

D． 不能加任何锁

Hydrogen is the fundamental element of the universe ______ it provides the building blocks from which the other elements are produced.

A．so that

B．but that

C．in that

D．provided that