they'll的意思是什么

造句：

1.They share weal and woe and are a veritable pair of brothers.

他们同甘共苦,是一对当之无愧难兄难弟。

2.Li asked for the most difficult task to be assigned to his company.

李连长要求把最艰巨任务交给他们连。

3.They are enjoying Berdovan's Fifth Symphony.

他们正在欣赏贝多芳的第五交响曲。