The operation proved to be very difficult这句中的prove是什么意思?它和The operation is very difficult表示的有什么区别吗?

the operation proved to be very difficult.it proved to be ___operation1 the difficult 2 a difficult选择哪一个,为什么 The operation proved to be very difficult这句中的prove是什么意思?它和The operation is very difficult表示的有什么区别吗? the operation,which lasted for over four hours,proved to be very difficult.请问prove to be是词组还是什么,不加to be行不行 prove difficult 和 prove to be difficult 有什么区别?The operation proved to be difficult.Rescue operations are proving difficult. 请教非限制定语从句与分词短语作定语之间的转换问题.是新概念二中的一句话,请问The operation,which lasted for over four hours,proved to be very difficult可不可以改为The operation lasting for over four hours proved 新2第76课 《木乃伊》：the operation 【proved】to be very hard!“这个手术被【证实】是非常困难的”请教明明是被动态 为啥不是was proved呢?而用了主动语态的动词形式proved?不是说只有 少数几个词 the requested clipboard operation the sameness in operation the operation has timed The operation has 翻译：The search proved difficult 新概念英语第二册的第77课中的一句话The operation,which lasted for over four hours,proved to be very difficult because of the hard resin which covered the skin.proved to be very difficult,to在这里是作什么用,另外be加形容词 After the operation什么意思 The operation has timed-out. columbus proved that the earth is round the fertilizer ()effective after tested in the fieldA,were proved B,were proved to be C,proved D,have been proved解释一下为什么及句子成分 What he said at the meeting ____trueA.proves B.is proved C.proved D.was proved 为什么? The search proved difficult和The search proved to be difficult有什么区别?