There are many people downstairs. What do you think _____?

A．to happen

B．happening

C．is happened

D．has happened

摄影镜头f值数字越大则光圈会怎么变化，景深会怎么变化（）

A、变大；变小

B、变小；变小

C、变大；变大

D、变小；变大