I was(be)in France in the summer of 1998.【 in the summer of 1998.过去时间,用一般过去式】
this is the first time I have seen(see)such a wonderful movies【this/it is the first time 和完成时连用,格式have done】
when he left,his mother was cooking(cook).【cook ,是持续性动词,之前过去式,所以用过去进行时,格式was/were doing,翻译:当他走的时候,他的妈妈正在烧饭】