在英语学习中,主语从句是由一个或多个单词组成的句子,通常由引导词引导,如that, whether, if, who等。主语从句通常出现在句子的开头或中间,而不会出现在句子的末尾,并且通常用动词的第三人称单数形式。通过以上几个方面的判断,我们可以准确地辨认句子是否为主语从句。
首先,主语从句通常被引导词引导,如that, whether, if, who, whom, whose, what, which等。例如:
- That he will come is certain. (that引导的主语从句)
- Whether he will come or not is uncertain. (whether引导的主语从句)
- If he comes, we'll go to the cinema. (if引导的主语从句)
- Who will come to the party is still unknown. (who引导的主语从句)
- What he said was true. (what引导的主语从句)
其次,主语从句通常出现在句子的开头或中间,而不会出现在句子的末尾。例如:
- Whether we should go to the concert tonight is still undecided. (主语从句出现在句子开头)
- It is uncertain whether we should go to the concert tonight. (主语从句出现在句子中间)
最后,主语从句通常用动词的第三人称单数形式,因为它作为整个句子的主语。例如:
- What he says is true. (主语从句用第三人称单数形式)