Mr. Wang, who is said to have immigrated to the USA, __ at No.2 Middle School in our city for twenty years.

A．has been teaching

B．was teaching

C．taught

D．has taught

边防支队、海警支队下辖有二个（含）以上基层党支部的司令部、后勤处可设立机关总支部，政治处设立机关党支部。