以下四个情景中，由光沿直线传播形成的是（　　）

A．湖中景物的倒影

B．眼睛被放大

C．日偏食

D．人在镜子中的像

________ you read English easily, you'll find it is another cup of tea to make conversation in English.

A．So long as

B．As soon as

C．Even if

D．Only if