若向量$\overrightarrow{a}$=(1,0,z)与向量$\overrightarrow{b}$=(2,1,2)的夹角的余弦值为$\frac{2}{3}$，则z=____ ，|$\overrightarrow{a}$-2$\overrightarrow{b}$|=____ 

2012年9月22日是杭州第六个“城市无车日”。无车日当日从早7时到晚7时，杭城对机动车进行限行。未来让广大市民顺利出行，杭州增加了公共自行车点储车数量，共有六万多辆免费单车供市民骑行。该活动的开展（     ）
①有利于增强人们的节能环保意识
②有利于减少环境污染
③符合可持续发展战略的要求
④有利于把经济增长转移到发展公共交通上来

    Whether in your life or work, the following things are not the reasons for you to feel embarrassed. It's OK and just move on.

⒈Mistakes while learning

    There will be times when you have people above you(a boss) or even next to you(a coworker) that will get really annoyed with you for“ruining"  something "important".____ Even if you make mistakes and get a punishment, persevere and push on. You do not need to be embarrassed for learning from your mistakes.

⒉Food choices

    People are different and have different taste buds（味蕾）.Whether it is healthy or not, food is a choice and it is part of life.____  You do not need to be embarrassed for food you do or do not like. Tell them, "It is a personal choice I have made, and I am committed to it.”

⒊Your past

    Allowing positive experiences to define, limit, improve, and outshine（凸显）you may cause you to be caught up in the past and unable to truly live in the present. Whether your history is positive, negative, or somewhere in between, don't hold on to the negative experiences and let it reflect your current behavior，____

⒋The clean lines of your car／home／workspace

    When everyone gets in the car, you realize your Starbuck bags are still on the floor. So what? Think about it this way: everyone has a "messy" aspect of their life. Maybe their home is completely clean, but the relationship with their spouse（配偶）is messy. Someone's car gets washed once a week, but his/her work life could use some help.____ We don't apologize to others about our personal limitations. By being outwardly embarrassed, it only brings more attention to the fact!

⒌Putting yourself first

    If you find yourself saying no to something or making up lies to get out of it,tell them the truth,  and don't apologize. You will feel much better in the long run if you are honest with them and yourself. If you're not up to a voluntary duty, you don't have to be. You can politely refuse the person's request.

    ____ Put yourself first.

A. It is simply a personal choice that people make for their own reasons.

B. It is okay to be selfish from time to time.

C. Errors are bound to happen when you have on your training wheels.

D. Each of them waits for your immediate help.

E. Let bygones(过去的事)  be bygones.

F. Forgetting history means betrayal.

G. No one on Earth lives a perfectly "clean" life in every aspect.