患者，女，50岁，因腰背疼痛3月余，检查MRI示脊柱多处转移瘤，建议进一步检查方法最有价值的寻找原发病灶的检查方法为（）。

A.SPECT

B.超声

C.CT

D.MRI

E.PET

Enshi is becoming a tourist city. _____ people come here during the holidays every year.     [ ]

A. Thousand of

B. Thousands of

C. Five thousands of

D. Five thousands