In Spanish, the present perfect form of ser describes a state of being that existed in the past, and might occur again in the future. The present perfect tense is used more in Spain than in Latin America. Make the present perfect using the present indicative form of the verb haber with the past participle of ser, which is "sido." For example, you might say, "He sido rico" to mean "I have been rich." The past perfect, or pluperfect, tense of ser describes a state of being that existed before another state of being in the past. For pluperfect, use the imperfect conjugation for haber plus the past participle sido. For example, you might say, "Habia sido pobre durante la infancia" to mean "She had been poor during childhood." The Spanish preterite tense is used to talk about states of being that occurred entirely in the past. Conjugate ser in this tense if someone was a certain way in the past, but is no longer that way. For example, you might say, "Fui rico" to mean "I was rich." Yo fui: I was Tu fuiste: You were El/ella/usted fue: He/she/you was/were Nosotros/-as fuimos: We were Vosotros/-as fuisteis: You all were Ellos/ellas/ustedes fueron: They/you all were In Spanish, the imperfect tense is used to discuss what someone was doing when they were interrupted or to describe past habitual actions. For example, you might say, "yo era pobre" to mean "I used to be poor." Yo era: I used to be. Tu eras: You used to be El/ella/usted era: He/she/you used to be Nosotros/-as eramos: We used to be Vosotros/-as erais: You all used to be Ellos/ellas/ustedes eran: They/you all used to be Even though "ser" is an irregular verb, it is conjugated using the regular rules that apply to all -er verbs for the conditional and future tenses. Conditional indicative is used to talk about a state of being that definitely will be true, as long as another condition is true. For example, you might say, "Yo seria rico si vendiera" to mean "I would be rich if I sold this product." The future indicative form is used for a state of being that will definitely exist in the future. For example, you might say, "Sere casado" to mean "I will be married."

Summary: Combine the correct conjugation of "haber" with "sido" for perfect tenses. Learn ser in the preterite indicative tense. Try the imperfect indicative for actions with no end. Use regular conjugation rules for conditional and future tenses.

If you need to remove oxidization from wires, a rosin-based solder is your best bet. As most electronics use more fragile, thinner wires, anything too corrosive may risk damaging them and shorting your circuit. Find a rosin-based solder at your local hardware store when working with electronics. If you're working with something bigger than electrical wiring, such as copper piping, you'll need something more corrosive. Acid flux or tinning flux will remove larger areas of oxidization and give you a much stronger soldering job. Tinning flux has small amounts of a powdered metal alloy mixed into the paste. The powder will melt with the flux and help fill the inside of the pipe you are soldering, making it more waterproof and longer-lasting. Leaded solder will melt at a lower temperature than other types, which makes it better for delicate electrical wiring. Ask at your local hardware or electronics store for leaded or electrical solder and you should have a small variety of types to choose from. Here are a few key differences in types of solder that may come up: Lead-free electrical solder will also work for small wiring projects. It is more environmentally-friendly as it doesn't contain lead, but also will not hold quite as strong. Some leaded solders will come with a rosin core. This means that they are slightly hollow and will have a thin line of rosin flux running through the middle. It will only be a small amount, so it shouldn't replace other flux, but it will increase the flux coating of your wires. Leaded solders that are solid all the way through and don't have a rosin core are also a solid choice. These may oxidize slightly more, but as long as you are using soldering flux they should still hold strongly for a long time. If you are using leaded solder, make sure to wash your hands once you have finished working with it as the lead is toxic. Silver has a much higher melting point than lead, so it works much better for larger soldering projects. Ask for pipe or silvered solder at your local hardware store when working with pipes. You should never use lead-based solder when working with piping that will carry water, as the lead is toxic and will make the water unsafe to drink. While lead-free solder may work when soldering pipes, it won't be as strong or as durable as silvered solder. Plug in or turn on your soldering iron to start heating it up. Once it is hot, use a damp sponge to clean away any solder left on the tip of the iron, making sure to never touch the hot end of the iron while it is on. Always keep your soldering iron in a stand while it is on. The tip will get very hot, so it shouldn't be allowed to rest on any surfaces as this may start a fire. Don't leave your soldering iron unattended while you are using it. Apply a small amount of solder to the end of your soldering iron once it has heated up and been cleaned. Once the tip is covered and has a shiny appearance, you can wipe away any excess on the same damp sponge. This is called "tinning" your iron and will stop it from oxidizing as you work with it. As pipes are much bigger and more solid than intricate wiring, a soldering iron may take a long time to heat a pipe up to the right temperature. Use a propane torch or something similar when soldering with pipes. For the best results, adjust the torch until you have a blue flame around 2 inches (5.1cm) long, and hold the tip of the flame to the pipes. Make sure you always light your blowtorch away from yourself and use proper safety precautions when working with it. Wear protective, tinted glasses, fire-proof leather gloves and flame-retardant clothing for extra safety. Getting the perfect temperature with a blowtorch may take more practice than when working with a soldering iron. If the flux you are working with begins smoldering and turns black, it's a sign you are using too much heat. If the solder doesn't melt when touched to pipes, you might not be using enough. Keep practicing until you get a sense of the right way to work.
Summary: Use rosin-based flux for electrical soldering. Go for an acid flux when soldering pipes. Opt for leaded solder when working with electronics. Choose silvered solder for soldering pipes together. Turn on your soldering iron and clean it when working with electronics. Go for a blowtorch when soldering pipes.