occur造句
If these drugs are stopped abruptly then some withdrawal symptoms may
occur.
如果突然停服这些药，则可能出现一些戒断症状。
Keep a pad handy to jot down queries as they
occur.
手边放一本便笺簿，以便有问题时随时记下。
Nitrates are chemicals that
occur naturally in water and the soil.
硝酸盐是水和土壤中自然存在的化学物质。