我個人認為 2 & 5 都沒錯. 我也常這麼說. 至於4, 我也覺得加上'有' 聽起來比較通順些. 加油!

2) 下个月他要回去北京。 5) 以前每年他都要到英国去过。 ------This two sentence has same point, that in Chinese, we use verb + direction to show whether this VERB is away from the SPEAKER or close to the SPEAKER. Away from the speaker, use "去” ,like "回去“ means the verb's destination is away from where the speaker is now. Close to use "来”, like "回来“means the verb's destination is close to where the speaker is now. When you want to add a object to this verb, the object should stick to the verb, then become "回北京去“ ”到英国去“, and this two verb"到，回” is away from where the speaker is now. If the speaker is in "北京，英国“，then the sentence become: 下个月他要回北京来。 以前每年他都要到英国来。 And 回 in Chinese means that place is the home of the person. 5) 以前每年他都要到英国去过。 The error of this sentence is 要 and 过。要means want to, 过means already done. They can't be used together. And 过 is finished, it can't be used together with "every 每”。It should be: 以前每年他都要到英国去。 or 以前他到英国去过。 4) 我们都觉得这课一点儿难。 -> 我们都觉得这课有点儿难 （i think this is correct) 一点儿is adj， qualify noun, 有点儿 is adv, qualify verb or adj. So here 我们都觉得这课有点儿难。 我只有这一点儿课。

2) 下个月他要回去北京。→回/去，选一个用。或者去掉“北京”。 4) 我们都觉得这课一点儿难。 -> 我们都觉得这课有点儿难 （i think this is correct)→有一点难 5) 以前每年他都要到英国去过。→去掉“过”，中文对时态的要求很低，不需要明显的过去式。

1.下课月他要回北京 2.U are right~ 3.以前他每年都要到英国去（Maybe sounds better）