conceive

我无法想象更可怕的事情。

I cannot ___conceive of anything more horrible.

出于某种原因，她两年都未能怀孕。

For some reason, she did not ___conceive for two years.

她尝试了多年，但从未成功怀孕。

She had been trying for years, but never managed to ___conceive.