在商务英语写作中，我们经常需要表达事情的必要性，以下是一些常见的必要性表达句：
- 工程应该在4月底完成。
Construction should be finished by the end of April. - 我们确实需要更好地控制成本。
We definitely need to get better at controlling the costs. - 我们的产品必须严格按规格生产。
We must have these items produced strictly to our specifications. - 我们需要换一个新部件。
We need to get a new part. - 我们要支付多少关税？
What kind of tariffs will we have to deal with？ - 您用不着穿正装，这是一个非正式场合。
You don't have to wear a suit.It's an informal occasion. - 您必须通知税务部门。
You must inform the tax authorities. - 你们每月的办公用品预算不应超过100美元。
Your monthly supply budget should not exceed$100.
