In developing a plan of care for a client with rheumatoid arthritis, the nurse should consider that clients with rheumatoid arthritis should be positioned so as to

A．prevent flexion deformities of the joints.

B．decrease edema around the joints.

C．promote maximum comfort.

D．prevent venous stasis.

有研究表明，生物达灭绝在历史上发生过二十几次，大约每2600万年发生一次，似乎具有______。对于物种大灭绝的发生是否真的如此频繁和有规律，还有争议。但即便是最______得孤寂，也认为至少有5次物种大灭绝是非常明显的。

A．必然性 乐观

B．规律性 简单

C．突发性 粗略

D．周期性 保守