多项选择题

A.前者为Ctrl+Alt+BACkspACe键,后者为Shift+Ctrl+BACkspACe键
B.前者为Ctrl+Shift+BACkspACe键,后者为Shift+Alt+BACkspACe键
C.前者为Ctrl+BACkspACe键,后者为Alt+BACkspACe键
D.前者为Shift+BACkspACe键,后者为Shift+Alt+BACkspACe键