Tom is the only one of the students who ____ going to swim this afternoon.

A．is

B．was

C．are

D．were

找出在职工年龄大于50的职工姓名，以及这些职2ET作所在的城市，正确的命令是 ( )。

A．SELECT 姓名,城市 FROM 职工; WHERE (年龄＞50) OR (职工.职工号=城市.职工号)

B．SELECT 姓名,城市 FROM 职工; WHERE (年龄＞50) AND (职工.职工号=城市.职工号)

C．SELECT 姓名,城市 FROM 城市,职工; WHERE (年龄＞50) OR (职工.职工号=城市.职工号)

D．SELECT 姓名,城市 FROM 城市,职工; WHERE (年龄＞50) AND (职工.职工号=城市.职工号)