there‘s nothing ungrammatical about ’from when‘, because the clause starting with ’when‘ is a perfectly legitimate noun clause (i.e., ’when agriculture began‘ serves as a noun. however:
- it’s possible that the gmat does consider such constructions wrong; the only way to tell is to see if they say so in any official answer choices
- regardless of where the gmat stands on the issue, ‘the beginning of agriculture’ is unquestionably better than ‘when agriculture began’ (i.e., an actual noun is almost always superior to a circuitous noun clause, when possible)
据留学360介绍，以上就是对于When引导的名词从句这一GMAT语法知识点的相关介绍，考生朋友不妨在遇到此类题型时对于文中的一些用法进行试验。
