Only when I began to do it ____ that I had made a mistake.A I realized B I had realize

Only when I began to do it ______ that I had made a mistake.

A．I realized

B．I had realized

C．did I realize

D．would I realize

Only when I began to do it ______ that I had made a mistake.

A．I realized

B．I had realized

C．did I realize

D．would I realize

Only then ______ that I had made a terrible mistake.

A) I realized B) did I realize

C) I had realized D) had I realized

Hardly ______ the office when it began to rain.

A) did I leave B) had I left C) I left D) I had left

______started mowing the lawn when it began raining.

A．No sooner I had

B．No sooner had I

C．Hardly I had

D．Hardly had I

I was like that ship beforemyeducation began, onlyIwas without compass or sounding-line, and had no way of knowing how near the harbor was. (省略)

A、had I got

B、I had got

C、had I arrived in

D、I had arrived at

Only after a year______ to see the results of my experiment.

A．I began

B．I had begun

C．have I begun

D．did I begin