"He does not drink tea in the mornings."
他早上不喝茶 vs. 早上他不喝茶 In English, I could say "In the morning, he does not drink tea" but in Chinese, my answer of "早上他不喝茶" was marked incorrect. Does Chinese grammar stipulate that "He, in the morning, does not drink tea" is the only correct ordering, or would my answer work?
Your answer should be correct. Moving the order of the time only changes the emphasis.
Huh, LearnChinese made it seem like time always goes first. How flexible is it?
It's completely flexible. The time can come either before or after the subject. The only difference is the emphasis.
He in the morning doesn't drink tea?! That seems wrong. Why won't it let me say He doesn't drink tea in the morning?!