Criticism and self-criticism is necessary _____ it helps us to correct our mistakes.

A．by that

B．at that

C．on that

D．in that

该图为一患者房角图，该房角属于（）

A.窄角Ⅰ级

B.窄角Ⅱ级

C.窄角Ⅲ级

D.窄角Ⅳ级

E.宽角