1、解决那些问题花了科学家们很长时间.
It took very long time for the scientists to solve those problems.
2、没有足够的锻炼人们无法保持健康.
Without enough practice,we can't keep health .
3、我妹妹经常带外国朋友参观她的厂.
My sister often show foreign friends to visit her factory.
4、如果你反复练习骑车,我相信你很快就会骑得很好.
I'm sure you can ride very well if you practice riding bike over and over.
5、如果你有任何困难,可以找我帮忙.
You can turn to me for help when you have any difficulty.
6、晚饭过后太长时间看电视对你的健康不利.
Watching TV too much time after supper is bad for your healthy .