The __________ rate has been rising in the past decade in China，________ is reported in a recent survey. People find it hard to maintain their marriage.

A．divorce; as

B．divorce; it

C．disconnection; which

D．separation; what

上颌乳尖牙的近中和下颌乳尖牙远中出现间隙称为

A．生长间隙

B．灵长间隙

C．替牙间隙

D．可用间隙

E．必须间隙