问题
选择题
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
答案
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。