协奏曲是指最初什么乐器和什么乐器互相竞奏的乐曲？
参考答案：
独奏乐器，弦乐器。
He is popular in his class. Because he _______ his classmates.
A. falls in love with B. gets on well with C. talks with
下列不出现颈静脉怒张的是
A．右心衰竭
B．左心衰竭
C．缩窄性心包炎
D．心包积液
E．上腔静脉阻塞综合征
