Teachers, train drivers, oil refinery workers and other French employees have _____to strike in protest of President Sarkozy’s pension (养老金) reforms.

A．connected

B．united

C．joined

D．attempted

下述"骨母细胞瘤"的描述，哪项错误（）

A.脊柱最常见

B.发生于脊柱者，主要侵犯椎体

C.肿瘤膨胀性生长

D.分中心型、骨皮质型和骨膜型

E.血碱性磷酸酶可升高