如图所示，天平右盘放砝码，左盘是一个水银气压计，玻璃管固定在支架上，天平已调节平衡，若大气压强增大，则(　　)

   Mrs. Black lives on Second Avenue. New Year is coming. She wants to send (寄) a card to her friend in Toronto, but she doesn’t know where the post office is. She asks her neighbor (邻居) Mary, “ Is there a post office near here? I want to send a card.”
   “The post office is not near from here,” answers Mary, “but you don’t need to go to the post office to post the card. There is a mailboxin front of the supermarket. You can put your card into the mailbox”