He gets up early every morning. Ancient people didn’t know the earth is round. If winter comes, can spring be far behind? When you meet him, tell him to call me. The meeting is at 8:00 tomorrow. Hurry up. Your plane takes off at 8:00. 归纳1：表示一个习惯性、经常性、长期性的动作 归纳2：表示客观真理。 归纳3：在连词when, before, until, if, as soon as, as等引导的状语从句中,常用一般现在 时代替一般将来时。 归纳4：表示计划、安排好（在时间表中）

Sum up the uses of the present simple tense and the present continuous tense.