每【měi】

每 means "every" or "each". Like a number, it needs a measure word before the noun – 每个人, 每本书 – except with words that are measures themselves, such as 天, 年, 次 and 周.

• × 每学生 → 每个学生
• × 每个天 → 每天

都 before the verb

When the 每 phrase is the subject or the object moved to the front, 都 has to go before the verb. It gathers up all the cases 每 lists.

• × 每个学生有一本书 → 每个学生都有一本书

With 每天, 每年 and other time words, 都 is usual but can be left out.

Where the time phrase goes

A time phrase with 每 goes before the verb, at the front of the sentence or just after the subject. English puts "every day" at the end.

• × 我喝咖啡每天 → 我每天都喝咖啡

每次 for "every time"

每次 + an event, then 都 + what always happens with it.