Not only his parents but also his brother           to the Summer Palace. They will be back next week.

A．have been

B．have gone

C．has gone

D．has been

特异性感染是指( )

A．金葡菌感染
B．铜绿假单胞菌感染
C．滴虫感染
D．结核杆菌感染
E．破伤风杆菌感染