Sexually transmitted diseases（STDs）are spread by sexual contact involving the genitals, mouth, or rectum, and can also be spread from a pregnant woman to her fetus before or during delivery. STDs, which affect both men and women, are a worldwide public health concern.
While most STDs can be cured, some cannot, including HIV（which causes AIDS）, genital herpes, and human papillomavirus（HPV）, which can cause genital warts.
STDs can be spread by people who don't know they are infected. Always use protection every time you have sex, until you are sure you and your partner are not infected with an STD.
If you are in a relationship, delay having sex until you are physically and emotionally prepared, have agreed to only have sex with each other, and have both been tested for STDs.
Questions to ask someone before having sex include：
发生性关系前需要回答如下的问题：
How many people have you had sex with？
你曾与多少人发生性关系？
Have you had sex without a condom？
你是否有过没有使用避孕套性交？
Have you ever had anal sex？
你是否有过肛交？
Have you ever had unprotected oral sex？
是否有过未采取任何安全措施的口交？
Do you have many sex partners？
是否有很多性伴侣？
Do you inject illegal drugs or have you had sex with someone who injects drugs？
是否注射毒品或是否与注射毒品的人发生性行为？
Have you ever had unprotected sex with a prostitute？
你是否与没有任何安全措施的妓女发生性关系？
Have you ever had an STD, including hepatitis B or hepatitis C？Was it treated and cured？
你是否曾经感染过性传播疾病，以及乙肝和丙肝？是否治疗或治愈？
Safe sex practices
安全性行为措施
Some STDs, such as HIV, can take up to 6 months before they can be detected in the blood. Genital herpes and the human papillomavirus（HPV）can be spread when symptoms are not present. Even if you and your partner have been tested, use condoms for all sex until you and your partner haven't had sex with another person for 6 months. Then get tested again.
Watch for symptoms of STDs, such as unusual discharge, sores, redness, or growths in your and your partner's genital area, or pain while urinating.
留意性传染疾病的各种症状，像疼痛、红肿、流脓或者生殖部位增生，以及小便疼痛。
Don't have more than one sex partner at a time. The safest sex is with one partner who has sex only with you. Every time you add a new sex partner, you are being exposed to all of the diseases that all of their partners may have. Your risk for an STD increases if you have several sex partners at the same time.
Use a condom every time you have sex. Latex and polyurethane condoms do not let STD viruses pass through, so they offer good protection from STDs. Condoms made from sheep intestines do not protect against STDs.
Use a water-based lubricant such as K-Y Jelly or Astroglide to help prevent tearing of the skin if there is a lack of lubrication during sexual intercourse. Small tears in the vagina during vaginal sex or in the rectum during anal sex allow STDs to get into your blood.
Avoid douching if you are a woman, because it can change the normal balance of organisms in the vagina and increases the risk of getting an STD.
如果你是位女士，避免用水灌洗阴道。因为这可能会破坏阴道内部正常的机体平衡，增加感染性病的几率。
Be responsible. Avoid sexual contact if you have symptoms of an infection or if you are being treated for a STD or HIV. If you or your partner has herpes, avoid sexual contact when a blister is present and use condoms at all other times.
