she was frightened and ___what was wrong with him,at once rang up the doctor.a not kowning b.didn't kown 答案是not kowning 为什么?

she was frightened and ___what was wrong with him,at once rang up the doctor.a not kowning b.didn't kown 答案是not kowning 为什么?
she was frightened and ___what was wrong with him,at once rang up the doctor.
a not kowning b.didn't kown 答案是not kowning 为什么?

she was frightened and ___what was wrong with him,at once rang up the doctor.a not kowning b.didn't kown 答案是not kowning 为什么?
A
分词短语在此作原因状语

not knowing表示当时的一种状态，而didn't know只表示时间上是过去发生的。好好思考一下吧！