occur的解釋：

　　v.發生;出現;存在;產生

　　第三人稱單數： occurs

　　現在分詞： occurring

　　過去式： occurred

　　過去分詞： occurred

　　occur的用法例句：

　　1. If these drugs are stopped abruptly then some withdrawal symptoms mayoccur.

　　如果突然停服這些藥，則可能出現一些戒斷癥狀。

　　2. Keep a pad handy to jot down queries as they occur.

　　手邊放一本便箋簿，以便有問題時隨時記下。

　　3. Nitrates are chemicals that occur naturally in water and the soil.

　　硝酸鹽是水和土壤中自然存在的化學物質。

　　4. Emergency cooling systems could fail and a reactor meltdown could occur.

　　緊急冷卻系統有可能失靈，核反應堆有可能發生堆芯熔毀。

　　5. Unless you respect other people's religions, horrible mistakes and conflict willoccur.