他之所以没有及时回复,是因为正在处理一件突发事务。Tā zhīsuǒyǐ méiyǒu jíshí huífù, shì yīnwèi zhèngzài chǔlǐ yí jiàn tūfā shìwù.The reason why he did not reply in time was that he was dealing with a sudden matter.
我之所以选这家餐厅,是因为它离公司很近。Wǒ zhīsuǒyǐ xuǎn zhè jiā cāntīng, shì yīnwèi tā lí gōngsī hěn jìn.The reason I chose this restaurant is that it is very close to the office.
她之所以每天早起,就是想多读一会儿书。Tā zhīsuǒyǐ měi tiān zǎo qǐ, jiùshì xiǎng duō dú yíhuìr shū.The reason she gets up early every day is that she wants to read a little longer.