阅读理解。

1. When does the train X504 leave Washington?

A.  9:00.

B.  9:30.

C. 10:00.

D. 10:30.

2. If you have to get to New York before 12:00, you'd better take _________.

A. X500

B. X501

C. X502

D. X503

3. Which of the following trains does not stop at BWI Airport?

A. X502.

B. X503.

C. X504.

D. X505.

4. If you want to go on weekends, you can NOT choose _________.

A. X501

B. X502

C. X503

D. X504

5. Which of the following is true according to the timetable?

A. You can have meals on most of the trains.

B. Most of the trains do not stop at Neward Int'l Airport.

C. You can't buy a ticket at the stations without reservation.

D. Nobody can get from Princeton Junction to Metropark on January 30.

女性，16岁，于右膝下方有一肿物，5年来逐渐增大，无痛，步态正常，X线片发现右胫骨内上方有一肿物，基底部有骨小梁与胫骨相连，基顶盖部致密度减低，边界尚可辨认。

根据以上症状，最可能的诊断是

A．骨肉瘤

B．骨巨细胞瘤

C．骨瘤

D．骨软骨瘤

E．骨转移瘤