Spirogyra is a large genus (about 400 species) of freshwater green algae found in shallow ponds, ditches and amongst vegetation at the edges of large lakes, generally growing free-floating.It often grows in short-lived ('ephemeral') ponds that build up during wet weather, and dry up subsquently.pirogyra is a large genus (about 400 species) of freshwater green algae found in shallow ponds, ditches and amongst vegetation at the edges of large lakes, generally growing free-floating.
General Past Tense Pronunciation Rule. An additional syllable with the -ed ending is only necessary when the last sound (not the last letter) of the base form of the verb is a /t/ or /d/; for example, wanted (two syllables), decided (three syllables), needed (two syllables), or invited (three syllables).etting Started â Adding -ed. When teaching English past tense pronunciation for regular Simple Past verbs, ESL and EFL students have to first be taught to add -ed to the end of the base form of the verb.
When syllables end in a vowel and then consonant (as in the examples above), the vowel is usually short. If there is more than one consonant, the vowel is almost always short. This becomes important as a way to keep the same vowel sound when adding-ed to put a verb into the past tense. We often double an ending consonant to keep a short vowel short. For example, the past tense of 'stop' is 'stopped.' Otherwise the silent 'e' rule below (which also applies when followed by 'd') would give it a long 'o' sound like soap or hope. See the Simple Past Tense explanation of spelling changes.