因为他没有雨伞用英语怎么说，3个语法点一看就懂

He doesn't have an umbrella.

This sentence demonstrates three key grammar points:

1. Subject-Verb Agreement: The subject "He" is singular, which requires the singular form of the verb "have." Thus, "has" is not used; instead, "have" is the correct form.

2. Article Usage: The article "an" is used before the noun "umbrella" to indicate that the umbrella is not specific or known to the speaker. "A" would be used if the noun were non-specific, but "umbrella" is a countable noun, so "an" is appropriate.

3. Negative Formation: The negative form of the sentence is created by adding "does not" before the base verb "have." The "not" is attached to "does," not "have," which is a common error in forming negative sentences in English.