Only when our country has aircraft carriers our distant islands more effectively.
A. we can guard
B. can we guard
C. we guard
D. do we guard
网友回答
A. we can guard
B. can we guard
C. we guard
D. do we guard
解析：考查倒装句。only +状语提前主谓用部分倒装。故排除A、C,根据意思，只有当我们国家有航空母舰时，我们才能够更有效地保护我们远方的岛屿。