Of the many challenges the Chinese government faces, one of the mostserious is the loss of arable land.

One of the most serious of the many challenges the Chinese government faces?is the loss of arable land.

你把黑體部分提前，便得到：

Of the many challenges the Chinese government faces, one of the most serious is the loss of arable land.

這個(gè)最高級常見的格式，把范圍定語提到句首，予以強(qiáng)調(diào)，同時(shí)照顧了句子結(jié)構(gòu)的勻稱。