The compromise over slavery in 1850 allowed ________ to enter the Union as a free state.
A、California
B、Maryland
C、Kansas
D、Maine
【正确答案】：A
【题目解析】：In addition, slavery was prohibited north of the southem border of Missouri. Another compromise over slavery came in 1850. Califomia had asked to join the Union as a free state. 参见教材P2014。
