1、否定词+比较级表示最高级含义，可强牺表示强调，例如I couldn't agree with you any more. There is no uglier face like that. Nothing is more difficult than that
2、It is/was+被强调部分+who/that+其他部分可表强调，例如It was an old bike that John bought yesterday in a marketplace
3、在上述句型中it没有词汇意义只是引出被强调的成分，如果被强调的成分是表示人的词，用who或that来连接都可以，如果是其他成分一律用that来连接
4、某些定语从句（或名词性从句）和强调句型形式差不多，容易混淆，如果去掉It is/was that结构框架后，句子仍然成立且通顺，则为强调句型，不成泥夏羞立或不通顺，则为定语从句或名词性从句
5、被强调成分是作主语的代词用主格，用作宾语的代针离词用宾格，例如it was he that helped me yesterday/ it was me that he helped yesterday
6、句型It is not until+被强调部分+that+其他部分表示直到...才...，例如It was not until yesterday that I learned it 直到昨天我才知道这件事
