1. Hundreds of valuable books (to go up) in smoke if this library (to catch) a fire. 2. If forest rangers (not to act) quickly, the fire (to get out) of control. 3. Often airplane patrols look for smoke. If a fire is spoted before it (to start) to spread, it (to be put out) quickly. 4. But if the fire (to be) too big, fire fighters are either (to fly in) by helicopter or (to parachute) to the site of the fire. 5. The fire (to move) by jumping from tree to tree. When it (to reach) the fire line it (to have) no place to go and (to stop). 6. Then for days and sometimes weeks afterward, fire fighters (to go) over the area until (there be) no more burning embers.
1. could go up, catched
2. don't act, can get out
3. starts, needs to be put out
4. is, fly in, parachute
5. moves, reaches, has, stops
6. go, there is
Объяснение:
:)