“不是……而是……”写原因特别好使，
只要加上“because或because of”就行
I recommend this book
not because of its humourous language,
but because it reveals some truth in our daily life
and strengthens my optimism to face challenges.
我推荐这本书，不是因为它的语言幽默，
而是因为它揭示了很多日常生活里的道理，
而且增强了我面对挑战的乐观。
I hope to express my sincere appreciation to him,
not because he helps me improve my grade,
but because of his tolerance, understanding,
encouragement and inspiration to me.
我想向他表示诚挚的感谢，
不是因为他帮助我提高了成绩，
而是因为他对我的包容、理解、鼓励和启发。
原因是句子用because，
原因是短语用because of
