Expressing "originally" with "benlai"
There are a number of ways to express "originally" in Chinese, and 本来 (běnlái) is one of the ones first learned, partly because its two characters are so simple.
Using 本来是 (běnlái shì) for a Change of Plans
本来 means "originally." Use it when you need to explain that happened unexpectedly later. Since the action has already happened, the 是... 的 construction is likely appropriate here. 是 is optional.
Subj. + 本来 + 是 +（不）[要 / 会 / 应该] + Verb + 的，[但是 / 可是 / 不过]...
- 我 本来 是 要 去 的，不过 后来 不 太 舒服 ，就 没 去 。I originally wanted to go, but I didn't go because I didn't feel very well.
- 这些 工作 本来 是 要 今天 做完 的 ，不过 明天 做 也 可以 。This work was originally supposed to be done by today, but it's OK to do it tomorrow.
- 我 本来 要 跟 他 结婚 的 ，可是 后来 发现 了 我们 真的 不 合适。I was originally going to marry him, but then I found that we are really not right for each other.
- 他 本来 是 应该 考 得 更 好 的 ，可是 那天 他 生病 了 。He would have done better on the test, but he was sick that day.
- 我们 本来 想 去 找 他 帮忙 的，可是 他 那么 忙 ，就 没 去 。We were going to go ask him for help, but we didn't because he is so busy.
Using 本来就 (běnlái jiù) for Emphasis of a Viewpoint
If you've got an opinion to express after stating how it "should be" or "should not be," then 本来就 will help you sound more convincing. The end of the sentence usually has an imperative or rhetorical question that leads to an opinion or suggestion, emphasizing the tone.
Subj. + 本来 + 就...
- 你 本来 就 够 瘦 了 ，还要 减肥 吗？You are already so thin and you still want to lose weight?
- 他 讲 得 本来就 不 对 ，为什么 还 要 我 听 他 的？What he says has always been wrong, so why do you still want me to listen to him?
- 她 本来 就 很 有钱，当然 买得起 了。She is rich. Of course she can afford it.
- 她 本来 就 不 喜欢 你，你 别 再 追 她 了。She never liked you in the first place, so stop pursuing her.
- 他 本来 就 很 喜欢 开玩笑，你 别 介意 。He has always liked joking around, so don't take it personally.
本来 (běnlái) with 就 (jiù) to Express "Duh!"
本来 (běnlái) is used to stress that the speaker believes something to be common knowledge. "Duh" is probably an overly saracastic and informal English equivalent, so another translation could be "it goes without saying." It's often easier to translate the feeling imparted by 本来就 as "supposed to," following it with a certain expectation.
Subj. + 本来 + 就 + 很 / 不 + Adj.
Subj. + 本来 + 就 + 会 / 要 / 得 / 应该 + Verb
- 照顾 孩子 本来 就 是 父母 的 责任。Taking care of children is supposed to be the responsibility of parents.
- 老师 本来 就 应该 好好 备课。Teachers are supposed to prepare their lessons well.
- 搬家 本来 就 很 麻烦。Literally, "Moving is supposed to be troublesome."Moving is always a pain.
- 生活 本来 就 很 不 容易。Literally, "Life was never supposed to be easy."No one ever said life was easy.