Write down these useful sentences,___________you'll forget them.( )
A.andB.orC.butD.so
He will call you when he in Beijing.
—What did our geography teacher say? —She told us that the earth _____ around the sun.
()He hardly goes to school by car, _________ he?
----________________? ----He’s very fine. Thank you.
--I can’t solve the math problem because it is too difficult. What should I do? -- _________ ask the teacher for help?