Fill in the blanks with the proper forms of given words.

I helped my mother to buy some beef and three____ (potato) for supper today.

"Belt and Road"（一带一路) are the two wings of developing Asia in the____ (twenty-one) century.

Please keep____ (silence) in the concert hall because people are enjoying Lang Lang's piano performance.

Candy ____ (lay) out the tea, fruit and snacks on the table and waited for the visitors.

.With the development of technology, mobile phones are ____ (wide) used these days.

—I found ______ under the desk.

填写量词。

一____云      一____叶子     一____叮咛 

一____微笑    一____大树     一____整体

 我市山亭区被评为“山东省长寿之乡”，特点之一是该地的山泉水多呈弱碱性，其pH约为（　　）