多根牙的抗力中心在（）

A.根分叉附近向根尖方向1～2mm

B.根分叉附近向方向1～2mm

C.根分叉附近向根尖方向3～4mm

D.根分叉下方1～2mm

E.根分叉附近向向2～3mm

The designer asked _______ we were getting on well with the project.

A．how

B．what

C．if

D．that