这是 现在分词完成形式的 独立主格 结构 所以 have要加ing. ���еĶ�������Ͳ���ing������ing����have been launched ����ν����ʽ���ɵ��Dz��о� ��Ӧ����һ���ȥʱǰ��Ӧ��and ��, and the most recent was launched at the end of last March.��֮ ����ing �Ͳ��� ���ڷִ� �Ķ�������ṹ��˼��˵�������������ӣ�����ing��û�������������ֲ�ͬ �ı�﷽�� ԭ�� �� �������� �ṹ ��״�� ��Ȼ˵�� �������Զ���Ҳ�����߼����� �� the most recent ��Ϊ �����Ѿ������ �� �� ���ڷִ� �������ʽ ��������� �򵥾� �����Բ������ʡ�ע�� ���� ��˼һ�� ע��ֱ�1��������ṹ2 �������Զ���Ӿ�3 ���о�1The country has already sent up three unmanned spacecraft , the most recent (of them )having been launched at the end of last March.2The country has already sent up three unmanned spacecraft , of whichthe most recentwas launched at the end of last March.3The country has already sent up three unmanned spacecraft , and the most recent (of them )waslaunchedat the end of last March. the most recent= the most recent one����ʱ������������һ�� ���ϸ����µ� �Ѿ����䡣��ʱ��״�����Ҿ��Dz��ܹ����the most recent���������޶��Զ���Ӿ䲻Ҫ�����of which���� ���޶��Զ���Ӿ�� ����� ��ʼӹ�ϵ����������û�����Ҳû�����ʣ�����the mostrecent �����߼�������ԭ������û�����Ҳû�����ʣ�����the mostrecent �������ڷִʵ��߼��������ɶ�������ṹ���Dz��Ǿ͹�����ν��ϵ������have��Ҫ��ing��� �� ���ڷִ� �� ��������ṹ ��Ȼ Ҫ�����ڷִ� �� his mother being ill ��he had to stay at home to look after her.=because his mother was ill ,he had to stay at home to look after her��Ϊ ���ڷִ� ���߼����� �� �������� ��һ������ �����ڷִ�ǰ�� �����Լ��� �߼����� �������ڷִʵ� ��������ṹ ����� һ�� ���������ڷִ� ��״���� being ill ��he had to stay at home ��=because he was ill ,he had to stay at home.