________ doing his experiment, he forgot to pick up his wife from the station. 

The boy’s bad behavior at school __________ his mother many sleepless nights.

 --- My son is learning English. What dictionary shall I buy for him? --- What about this one? It is __________ for beginners.

Every year, ____ graduates take pan in TOEFL for further education abroad.

---Does tiredness or inadequate sleep cause dark circles under eyes?---Lack of sleep will _______ making your skin look pale, and this will make your circles look darker.