如图所示，$△ABC$内接于⊙O，AD是⊙O的直径，$\angle ABC=30°$，则$\angle CAD$=____ °.

根据短文内容，完成下面各题，每空词数不限 
My English teacher is Mary. She is from England. Her father is Nick and her mother is Rose. They are very old. So they don’t work now. Mary has two children, a son and a daughter. Her daughter is Betty. Her son is John. Mary and her daughter are in China, but her husband Paul Smith is in England. Her son is in America. Paul is a police officer. John is a college student. Betty and I are in the same school. We are classmates. We are in Class Three, Grade Seven.
Betty is Mary’s____ .
Betty’s father is a ____  (职业).
____ teaches the writer(作者) English.
Mary comes from ____  .
Nick and Rose are Mary’s ____  .

填数游戏。

游戏规则：

①每个空格中，只能填1，2，3，4中的一个。

②每一横行、每一竖行的数字不能重复。

海水是巨大的资源宝库．如图所示利用海水为原料可获得许多化工产品：

下列各句中，没有语病的一项是（    ）