under-, 在下面，pin, 别针，固定。引申义固定根基，加强。

1. Producers have, therefore, preferred term sales contracts to underpin upfront investment.

因此, 生产商青睐长期销售合约,以保证前期投资.

2. That reality must underpin our partnership.

这一现实必须支撑我们的合作伙伴关系.

3. That really must underpin our partnership.

我们的伙伴关系必须基于这一现实.

4. There are, however, two secular trends that underpin the growth in the industry.

然而, 有两项长期因素支撑着这行业的增长.

5. Candour has its place in foreign policy, but it requires a strategy to underpin the rhetoric.

在外交政策方面,坦诚很重要, 但这种言论必须有相应策略作为基础.