300 dollars is a large amount of money，but it is ——than we need

填less.

这里是个转折.短语less than表示不到,少于

例句与用法:
1. This piece of furniture is really inexpensive with a price of less than forty dollars.
这件家具还不到四十美元，实在不贵。

2. Even under the best conditions, we couldn't finish in less than three days.
即使在最好的情况下，我们也无法在少于三天的时间内完成。

3. The amount by which one quantity is greater or less than another.
差额一个数在数量上多于或少于一个数的数值

300 dollars is a large amount of money，but it is —less—than we need

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