| 例句 |
These chemical changes occur naturally.这些化学变化是自然发生的。These are physical changes while those are chemical changes.这些是物理变化而那些是化学变化。The chemical processes involved in the experiment are extremely complex.该实验中的化学变化极其复杂。A chemical change has to take place before the energy can be let loose.能量释放，必须有化学变化。 |