如果我当时有空，我一定会应邀的。

If I were free, I would accept your invitation.

Source: Tatoeba

Sentence Composition

1 如果 rúguǒ
  1. if
  2. in case
  3. in the event that
2 我 wǒ
  1. I
  2. me
  3. my
=3 当时 dāngshí
  1. then
  2. at that time
  3. while
=3 当时 dàngshí
  1. at once
  2. right away
4 有空 yǒukòng to have time (to do sth)
5 我 wǒ
  1. I
  2. me
  3. my
6 一定 yīdìng
  1. surely
  2. certainly
  3. necessarily
  4. fixed
  5. a certain (extent etc)
  6. given
  7. particular
  8. must
=7 会 huì
  1. can; to have the skill; to know how to
  2. to be likely to; to be sure to
  3. to meet; to get together
  4. meeting; gathering
  5. (suffix) union; group; association
  6. (bound form) a moment (Taiwan pr. huǐ)
=7 会 kuài (bound form) to reckon accounts
8 应邀 yìngyāo
  1. at sb's invitation
  2. on invitation
=9 的 de
  1. of; ~'s (possessive particle)
  2. (used after an attribute when it modifies a noun)
  3. (used at the end of a declarative sentence for emphasis)
  4. (used after a noun, verb or adjective to form a nominal expression, as in 皮革的 pígéde "one made of leather" or 跑堂儿的 pǎotángrde "a waiter (literally, one who runs back and forth in a restaurant)" or 新的 xīnde "new one")
  5. also pr. dì or di in poetry and songs
=9 的 dī a taxi; a cab (abbr. for 的士 dīshì)
=9 的 dí really and truly
=9 的 dì (bound form) bull's-eye; target