句型转换。(o6B4n
He saw some public signs in the park .（改为否定句）(o6B4n
He /t.?/K'r.T4N2]'B/}(l/a)l.|9F1E-h9b*U4^.d'b1V-j*Z6F;L4p public signs in the park .(o6B4n