同时性指两个或多个事件在同一_________发生,并发性指两个或多个事件在同一_________发生。
You can _____ some bottles of wine, or some chocolates, or a bunch of flowers.
— ___________________
— Once or twice a week.
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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