类风湿性关节炎可见（）

A.梭状指

B.杵状指

C.爪形手

D.匙状指

E."X"形腿

Mrs. Pearson cut judy’s hot dog into eight pieces and Sylvia’s into six pieces. Sylvia cried because she felt she wasn’t getting as much hot dog as Judy. Piaget would say that Sylvia doesn’t understand the principle of()

A．Conservation

B．Accommodation

C．Egocentrism

D．Object permanence