... Humans must keep water, air, and land clean Water, air, and land must be kept clean .2. Governments must stop illegal trade of whales. Illegal trade of whales must be stopped .EXERCISE1. I ... have to use a Tài Liệu Dùng Kèm SGK 12 By giao su p1S + MODAL + V0 Would, can, will, must , Unit 10 – ENDANGERED SPECIES Language focusdon’t have to Need + To V0 ≠ don’t need to V0)Need ... something to protect the environment, _______ we?a. must b. need c. will d. shall4. I will do everything. You _______ do anything unless you really want to. a. may b. needn't c. must d. ought to 5....