A:yet; yet
B:already; already
C:already; yet
D:yet; already
①是集体的精神动力之源
②引领集体成员团结一致,开拓进取
③能够保证每个集体成员自觉承担集体责任
④是推动集体发展的内驱力
—Is this your pen, Sam?
—No, it's Peter's. _______ is in my pencil case.