You'll do much better _____ you are more careful with your spelling.
A：if
B：before
C：although
D：unless
“真正的朋友，在你获得成功的时候,会为你高兴,而不捧场；在你遇到不幸或悲伤的时候，会给你及时的支持和鼓励；在你有缺点可能犯错误的时候，会给你正确的批评和帮助。”高尔基的这一名言启示我们 ( )
By mentioning Muhammad Ali's words, the author intends to tell us that.
750×36＝____
25×36＝____
150×18＝____
150×72＝____
