My parents want me to take_________maths lessons at the weekend, but I want to play and have fun.

A．extra

B．available

C．former

D．recent

革兰染色阴性的厌氧菌是（）

A.肺炎链球菌

B.难辨梭状芽孢杆菌

C.龟分支杆菌

D.铜绿假单孢菌

E.厌氧球菌