A teacher must have a healthy body, the skills of a farmer, the mind of a scientist, the interest in art, and the spirit of social reform.

The heart has its reasons which reason knows nothing of.

I have now taken a serious task upon myself and I fear a greater one than is in the power of any man to perform.

The ethical implications of genetic modification must be carefully considered.

气候变化是我们这个时代最大的挑战之一，我们必须立即采取行动。