i think___important for students to learn some knowledge about Mars A.it B.what C.that D.thisimportant前没有be动词

i think___important for students to learn some knowledge about Mars A.it B.what C.that D.thisimportant前没有be动词 We all think___important for more people to know about bird's problemsA.that B.it C.them D.this应该选B it后面不加is了吗 这里的think难道是系动词? i i I I, I I I i i i i -I I i i i