I was almost asleep last night when I suddenly heard someone ______ at the door.

A．be knocking

B．knocking

C．to knock

D．having knocked

双眼低视力（）

A.双眼最好矫正视力都＜0.05

B.双眼中较好眼的最好矫正视力＜0.3，但≥0.05，另眼≥0.3

C.双眼中一眼最好矫正视力＜0.05，另一眼≥0.05

D.双眼矫正视力都＜0.3，但≥0.05

E.双眼最好矫正视力都＜0.1