有两个很好的理由我们不能做这件事。首先，我们没有足够的钱，其次，我们没有足够的时间。

There are two very good reasons why we can't do it. ___Firstly, we don't have enough money, and secondly, we don't have enough time.

我认为这适合我们，首先是因为它是很好的工作经验，其次是因为我们可以获得书籍和CD的折扣。

I think it would suit us, ___firstly because it is good work experience, and secondly because we can get discounts on books and CDs.

计划旅行时，考虑几个因素。首先，决定你的预算。

When planning a trip, consider several factors. ___Firstly, decide on your budget.