怪不得他中文这么好，原来他在中国住过十年。
guàibude tā zhōngwén zhème hǎo ， yuánlái tā zài zhōngguó zhù guo shí nián 。
No wonder his Chinese is so good: he lived in China for ten years.
怪不得这么冷，原来下雪了。
guàibude zhème lěng ， yuánlái xiàxuě le 。
No wonder it's so cold: it's snowing.
怪不得她不高兴，原来考试没考好。
guàibude tā bù gāoxìng ， yuánlái kǎoshì méi kǎo hǎo 。
No wonder she's unhappy: her exam didn't go well.