Rules to play Finswimming
Finswimming which is often compared to sports swimming differs from that sport in the use of masks, fins, snorkels and underwater breathing apparatus. This reflects the sports origins in the underwater diving techniques of snorkelling, breathhold diving and open circuit scuba diving.
Apart from requiring the use of a mask for protection of the eyes and for the ability to see underwater, the international rules have no requirements regarding selection. Centremounted snorkels also known as front snorkels are the only type approved for use subject to meeting minimum and maximum sizes. Fins are also regulated by the international rules. Monofins have a maximum size which can be checked by the use of a template while bifins must be one of the brands certified i.e. homologated by CMAS.
Underwater breathing apparatus is restricted to open circuit scuba using compressed atmospheric air as the breathing gas. The use of oxygen enriched mixtures is forbidden. Cylinders are limited by maximum cylinder pressure rating of 200 bar and a minimum cylinder capacity of 0.4 litres. While there are no requirements for regulators, swimmers appear to be free to modify these to remove any unnecessary parts
Both yet and already are used with the present perfect tense. Already is usually used in positive sentences. Yet is usually used in questions and negative sentences.
Imagine that you and your friend are going to travel. There are many things to do, and you ask your friend if he has done these things: Have you bought the tickets yet? Have you arranged a taxi yet? Have you reserved the hotel room yet? Have you packed the bags yet?
In all the examples, use yet at the end of the question. Your friend might answer: Yes, I've already bought the tickets. Yes, I've already arranged a taxi. No, I haven't reserved the room yet. No, I haven't packed the bags yet.
Use already in the positive answers, and yet in the negative answers.
There is one time you can use already in questions: it's when something happens earlier than expected. If your son finishes his homework in just 15 minutes, you could ask: "Have you already finished your homework?!" because you were expecting it to take more time.