Điền giới từ thích hợp `1` . Books are useful _______ the childern `2` . I spend a lot of money _______ Scholl things . `3` . We spend few days _______ Nha Trang beach `4` . My daughter always helps me ______ my housework `5` . Smoking is bad ____________ your health `6` . Doing exercise is good ________ For your body `7` . Hoa is good _____ drawing and coloring `8` . We are interesting __________ playing chess `9` . She often helps people _______ every thing `10` . They often bad at test