If the operation ________ carefully prepared, it would not have been successful.
A、wasnotC
语法题：虚拟语气。
Wateriscomposed_______hydrogenandoxygen.
It rained hard yesterday, ______ prevented me from going to the park.
The meeting _____ next week will be of great importance.
Itrainedhardyesterday,______preventedmefromgoingtothepark.
I don ’ t need any help at the moment,but I _____your offer.
