と　おもいます

My Japanese teacher thinks my dad is handsome.
にほんごのせんせいはおとうおさんがかっこいい(or はんさむだ)とおもいます。

(*When we talk about the third person's feeling, I would say おもっています.)

I think Japanese language is hard.
にほんごはいそがむずかしいとおもいます。

I think a car is convenient.
くるまはべんりだとおもいます。

I think my sister gave this jean to me.
いもとうがはこのジーンズをくれたとおもいます。

I think this is rabbit.
これはうさぎごだとおもいます。

Very good! Please keep up.