Please restrain yourself from smoking and spitting in public places,since the law forbids them.
中文：请不要在公共场所吸烟以及随地吐痰!这可是违法的!
或者简洁的翻译：法律禁止在公共场所吸烟和随地吐痰!
restrain 是及物动词 vt.制止[from] 做…
例句：They restrained him from interfering.
他们制止他干预此事.