She found it difficult to make friends because of her natural reserve.

　　她因天性矜持很難交到朋友。

　　He thought social inequality was all part of the natural order of things.

　　他認為社會不平等完全合乎事物的自然規律。

　　She was the natural choice for the job.

　　做那份工作，她是當然人選。

　　The body has natural defence mechanisms to protect it from disease.

　　人體對疾病具有先天性防御機制。