When the field surface is covered by gravel, soil erosion caused by rain and strong winds can be effectively prevented.（ ）
举一反三
- 中国大学MOOC: Smallpox can be effectively prevented by _______.
- The lnductrack Ⅱ design can produce a very strong magnetic field even when the train runs more slowly by ______.
- Plants will ( ) in a fertile soil when plenty of sunshine and rain is available.
- Soil erosion means
- Smallpox can be effectively prevented by _______. A: vaccines B: penicillin C: antibiotics D: vitamines