—Yes, it (is/are).

    There are many postcards from China. Look at this one. This is the Dongting Lake. It's in Hunan. It's a beautiful lake in China. Look at this square. It's Tian'anmen Square in Beijing. And this one is the Great Wall. It's famous too. It's more than twenty thousand kilometres long. There is a famous mountain in Anhui. It's the Huangshan Mountain.

⑴The Huangshan Mountain is high.  A.

⑵The Changjiang River is long.      B.

⑶The West Lake is beautiful.        C.

⑷The Great Wall is strong.          D.