Comparative/Superlative adjectives

My sister is 2 years (young) than me

Do you know what (slow) animal in the world is?

I think spring is (beautiful) season of the year.

Math is (important) to me than biology

Helen is (good) ballet dancer in our city

That test was (difficult) than the previous one last week

English is (easy) for me than Chinese

My phone is (expensive) than my sister's phone

Mary is (clever) than Ben

Who is (bad) runner: Tom or Sam?