填空题

A—acceptance letters
B—adjustment letters
C—application letters
D—collection letters
E—complaint letters
F—credit letters
G—inquiry letters
H—memorandums
I—order letters
J—reference letters
K—sales letters
L—news releases
M—annual reports
N—feasibility reports
O—investigative reports
P—progress reports
Q—trouble reports
R—trip reports ______调查报告 ______事故报告