Questions 1 to 5 are based on the following conversation.

A. Persevering is the key in getting these special accommodations.
B. Working from home is a pressing need for many members of the staff.
C. Frankness is often a good policy in negotiating with bosses.
D. Flexibility of schedule is an accommodation, not an entitlement.

美国全面发动“冷战”的标志是（）。

A、“铁幕演说”

B、杜鲁门主义的提出

C、马歇尔计划的出台

D、《北大西洋公约》的签订