BrainPOP is an educational program consisting of briefanimated videos _____ a man named Tim and his robot friend Moby discuss varioussubjects.

You will fall behind others ____________ you work hard.

Can you think of some casespeople are likely to tell lies?

(2013·甘肃河西五市二模)In the middle of the forest ________， in which we often went fishing when I was a little child.

Though ________ money, his parents managed to send him to a key university.[ ]