问题
选择题
已知2x+3y-2=0，则9x+27y+1的最小值为（ ）
A．-4
B．4
C．7
D．-7
答案
由题意，2x+3y=2，
又9x+27y+1=32x+33y+1≥2
+1=6+1=7，等号当2x=3y=1时取到3 2x+3y
故选C
搜题请搜索小程序“爱下问搜题”
已知2x+3y-2=0，则9x+27y+1的最小值为（ ）
A．-4
B．4
C．7
D．-7
由题意，2x+3y=2，
又9x+27y+1=32x+33y+1≥2
+1=6+1=7，等号当2x=3y=1时取到3 2x+3y
故选C
On a trip to California，my family stopped for lunch.As we walked toward the entrance to the restaurant，a man，with a____beard and dirty hair，jumped up from a bench outside the restaurant and opened the door for us.Regardless of his____，he greeted us in a friendly way. Once inside，my daughters whispered，“Mom，he ____.”After we ordered our lunch，I explained，telling the kids to look___the dirt.We then watched other customers approach the restaurant but many____him.Seeing this rudeness truly upset me.The day I became a mother，I had determined to set a good____to my children.Yet sometimes when things didn’t go right，being a good example was ____.When our meal arrived，I realized I had left the carsick pills in the truck.With the windiest trip ahead，the kids needed them，so I____myself from the meal and went to get them. Just then，the “doorman” was opening the door for a couple.They rushed past him without even acknowledging his____.Letting them in first，I said a loud “thank you” to him as I____. When I returned，we talked a bit.He said he was not allowed inside____he purchased food.I went back and told my family his____.Then I asked our waitress to add one soup and sandwich.The kids looked____as we had already eaten，but when I said the order was for the “doorman”，they smiled.When it was time to____ our trip，I found the “doorman” enjoying his meal.Upon seeing me，he stood up and thanked me heartily.He then____ out his hand for a handshake and I gratefully accepted.I suddenly____the tears in his eyes—tears of gratitude (感激)．What happened next drew great astonishment：I gave the “doorman” a____.He pulled away，with tears____down his face. Back in truck，I fell into deep thought.While we can’t choose many things in life，we can choose when to show gratitude.I said thanks to a man who had____held open a door for me，and also said thanks for that ___ to teach my children by example.
|