為了觀測星象，他建了一座瞭望台。

He built an observatory to study the stars.

Source: Tatoeba

Sentence Composition

1 為了 wèile for; for the purpose of; in order to
2 觀測 guāncè
  1. to observe
  2. to survey
  3. observation (scientific etc)
3 星象 xīngxiàng aspect of the celestial bodies (used for navigation and astrology)
4 他 tā
  1. (third-person singular) (since the early 20th century, usu. male) he; him; his
  2. (bound form) other; another; some other (as in 他日 tārì and 他人 tārén)
5 建 jiàn
  1. to establish
  2. to found
  3. to set up
  4. to build
  5. to construct
=6 了 le
  1. (completed action marker)
  2. (modal particle indicating change of state, situation now)
  3. (modal particle intensifying preceding clause)
=6 了 liǎo
  1. to finish
  2. (used with 得 dé or 不 bù after a verb to express (im)possibility, as in 忘不了 wàngbuliǎo "cannot forget")
  3. (literary) (usually followed by a negative such as 無 wú or 不 bù) completely (not); entirely (not); (not) in the least
  4. to understand clearly (variant of 瞭 liǎo)
=6 了 liǎo
  1. (of eyes) bright
  2. clear-sighted
  3. to understand clearly
=6 了 liào unofficial variant of 瞭 liào
7 一 yī
  1. one
  2. single
  3. a (article)
  4. as soon as
  5. entire; whole; all; throughout
  6. "one" radical in Chinese characters (Kangxi radical 1)
  7. also pr. yāo for greater clarity when spelling out numbers digit by digit
8 座 zuò
  1. seat
  2. base; stand
  3. (bound form) constellation
  4. (archaic) suffix used in a respectful form of address (e.g. 師座 shīzuò)
  5. classifier for large immovable objects such as buildings, mountains, bridges etc
9 瞭望台 liàowàngtái
  1. observation tower
  2. lookout tower