— Jack,you look tired today. What's wrong?

— I was _____ busy _____ I didn't go to bed until midnight yesterday.[ ]

A. so ; that

B. such ; that

C. too ; to

节流孔作用是（）

A.控制液压管路的充油时间

B.相关电磁阀打开泄油时，避免液压管路压力迅速下降

C.避免因某个部件故障漏油时，使系统油压下降

D.以上都对