Long-term investing is risky, and careful planning is imperative. 长期投资风险很大，谨慎计划至关重要。

it is imperative (that) It is imperative that these claims are dealt with quickly. 这些要求必须尽快解决。

it is imperative to do sth It was imperative to maintain peace and stability in the region. 当务之急是保持该地区的和平与稳定。