When did Abraham Lincoln announce an order to free the slaves

单项选择题The purpose of the speaker is to（）

A. introduce how to build a statue
B. introduce how to pass a statute
C. introduce the history of the Statue of Liberty
D. show the friendship between countries

单项选择题When did Americans celebrate May Day（）

A. The 1st of May.
B. The 1st of September.
C. The 1st Monday in September.
D. The 1st Monday in May.

单项选择题What is The National Underground Railroad Freedom Center

单项选择题Why was the Statue of Liberty closed in 2001（）

A. Because it couldn’t endure the test of time and needed repairing.
B. Because it was threatened by terrorist attacks.
C. Because it was damaged by tourists.
D. Because it would endanger the visitors.