He said that the work to improve crop production must continue.

VOA: special.2009.11.10

And you assumed that he must work out.

你认为他肯定常常锻炼。

Do you 课堂 - SpeakingMax英语口语达人

On his 95th birthday, he told VOA that the work to improve crop yields must continue.

VOA: standard.2009.09.16