This is my school. There are many trees and flowers in it. It's very beautiful. The teaching building is big and tall. There is a big playground in our school. After 4:30 in the afternoon, many students come to the playground to play football and some students play table tennis in the table tennis room. There are 1,200 students and 25 classes in our school. The students all like to study. The teachers in our school are very good. They help the students to study and the students like them, too

已知实数x、y、z满足2x²+3y²+6z²=a（a＞0），且x+y+z的最大值是1，求a的值．

（____）1. A. Tuesday   B. Thursday   C. tomorrow

（____）2. A. ping-pong  B. cartoon    C. football

（____）3. A. me       B. his        C. her

（____）4. A. morning   B. afternoon   C. birthday

（____）5. A. erhu      B. robot      C. piano