麻烦帮忙翻译一下几句高中的句子.中译英.

在解决了一个又一个问题之后,科学家们终于在试验中取得了重大成就.
After solving the problems one after another,the scientists finally gained great achievements on the experiment.

我发现很难与那些固执己见的人合作.( ...it...;insist )
I find it is hard for me to cooperate with some one who insists on its own.

自对外开放后,中国就成了吸引世界各地经商者的巨大市场.
Ever since opening up to the outside world,China has become a big market that attracts the business persons from all over the world.

到贝多芬出名的时候,他已经病的很严重了. ( be the time )
Beethoven was heavily ill by the time he became famous.

全世界人民逐渐意识到维护和平是很重要的.( come to realize )
The world come to realize the maintaining of peace is very important