用反证法证明“若a⊥c，b⊥c，则a∥b”，第一步应假设（　　）

    Whether you're a child, teenager, young adult or are middle-aged, respecting your parents is an important value. Your parents are the people who raise you, devoting time, energy and money to your development.____Whatever your age, there are 4 ways to show respect.

    Respect their belongings.

    One important way to show respect is to show regard for the things important to your parents. For younger children, this may mean not touching jewelry or other valuable things.____Don't take advantage of your parents' kindness and generosity. And never borrow things without asking first.

    Punctuality

    ____Therefore, always be on time. For teenagers, showing up on time means coming home by curfew (宵禁). Adult children should show up on time for family dinners or events, or to pick a parent up for a medical appointment. Call if you're going to be late because parents worry about children, whatever their age.

    ____

    Remembering birthdays, anniversaries and other special days is a sign that you honor your parents. Make plans to take them to lunch or dinner or bake a cake or cookies. Most parents don't expect expensive gifts, but a handmade gift is always appreciated, a phone call from a grown child who lives too far for a visit is a welcome sign of respect.

    Be kind.

    Kind words and affection are simple ways to show respect. Tell your parents you love them. Listen and allow your parents to speak without interruption. Show a sincere interest in what your parents have to say. Be patient with your parents and don t rush them. Never talk back or be rude or disrespectful. Acknowledge your parents' achievements. ____

A. Parents should help children build self-confidence.

B. Celebrate with them.

C Lateness shows a lack of respect.

D. Treat your parents the way you would like to be treated.

E. And they love you unconditionally throughout your life.

F. Being respectful helps build positive relationships with others.

G. For grown children, respect may mean returning a borrowed tool in good condition and on time.

How to Protect Your Ears

    You and your friends are leaving a concert on a Friday night. When you get outside, your ears are ringing. You have to shout to be heard. ____ So no harm done…right?

    Not quite. Temporary buzzing may be easy to ignore, but repeated exposure to loud noise will eventually cause serious— and irreversible(无法治愈的)—hearing loss. A new study conducted by researchers at Brigham and Women's Hospital in Boston shows that one in five people between the ages of 12 and 19 are experiencing slight hearing loss, and one in 20 have mild hearing loss. ____

    But the good news is that there plenty of ways you can protect your ears from further damage — and still listen to the music you love:

    Ask around. Put your earbuds in or your headphones on, and then ask a friend next to you whether or not he or she can hear what you're listening to. ____ Turn it down.

    Buy noise-canceling headphones. A pair of earbuds or headphones that fits comfortably will limit outside noise so that you can hear your music better at lower volumes.

    Take breaks. ____ So when listening to music, take your headphones off for 15 or 20 minutes and let your ears enjoy the quiet.

    ____ You can buy a cheap pair at any drugstore as an easy way to lower volume at concerts — or while playing or practicing your own music — without changing the quality of the sound.

A. Use earplugs.

B. Keep the volume below 70 percent.

C. If the answer is yes, your music is too loud.

D. Like every other part of your body, your ears need rest.

E. But by morning, your hearing is totally back to normal.

F. Unfortunately, there's no way to get back hearing you've already lost.

G. The exposure to noise is louder and longer than in any previous generation.