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.