15. My brother thinks getting up early in the morning is difficult.

S + think(s) + Ving .. + be + ADJ 

16. It takes me fifteen minutes to ride from my house to Mr. Quynh's class.

It takes + O + time + to V: mất bao nhiêu thời giam làm gì

17. It takes my younger sister two hours to do her homework every night. 

18. While my parents are away, my grandparents always look after us. 

take care of = look after: chăm sóc

19. Are you interested in practicing English with native speakers? 

Be interested in + Ving: thích 

20. He is lazy so he always gets bad marks.

Clause + so + clause: vì vậy