The plain form of “to find” is 見付ける so it would be 見付けました or 見付けていました if you want to use the 〜て form.
乗る is intransitive so it would be 自転車に乗る (to ride a bike). Also, the stem of 乗る is 乗り. So it would be kind of like this:
トレイルに自転車に乗りに行きます
I’m going to ride my bicycle along/down the track/trail.
I think it being or not being transitive might be a little misleading, apologies. The “exiting” verbs like 出る and 降りる are also intransitive, but they can use を to mark the object on which exiting is done. 乗る doesn’t, but it might have more to do with it being a motion verb, not sure.
This weekend, I bought a lot of JoJo lottery tickets. Yikes… Now I have 4 glass plates. All the Twitter fujoshi also bought lots of tickets. On Mercari, they’re selling the things they don’t want. The things they don’t want are yhe things I want. Of course. At cheap prices too. my poor wallet.
A few years ago, I stopped watching much TV other than sports. なくなる: “to no longer do/be”. Formed per above with verbs and い-adjectives; nouns and な-adjective stems take では- or じゃ- to form a negative with ~なくなる. Emphasizes a process or turning point more than simply using もう with a negative to say “not ___ anymore.”
I just started working through もう and まだ in Genki and I have an impression that your original suggestion with 〜たことがある/〜たことがない makes the most sense. The past progressive with まだ〜ていない seems like something one would use to talk about past events which can be completed (drinking coffee, reading a book, etc.) and “I haven’t used this grammar structure yet” is more of a general expression which fits the “experience” context of 〜たことがある.
I figure まだ〜ていない is more of a “I haven’t had breakfast yet” kind of deal, but it could be applied to using grammar points as well as sort of an offhand “oh I know about it, I just haven’t gotten around to using it in a sentence yet” kind of thing, I guess.
But if you’re attaching some significance to whether or not you’ve used a grammar point in practice, まだ〜たことがない may well be a better fit. In all honesty though, I think in this particular case either will bring your point across and it doesn’t matter all that much which you use.
〜と考えられている means “is considered …” or “is thought of as …”
It would also be possible to use 〜と思われている with the same meaning, or 〜とされてい with roughly the same meaning but carrying the nuance of being a generally accepted consensus across a large number of people. In this case I think that doesn’t fit very well, since most people know people with glasses aren’t actually smarter than others.
I’m guessing this should be 空港で会えない? Generally speaking things marked by に with 会う are animate things you can interact with. Using で would be “meet at the airport” as opposed to に and “meet the airport.”
どちら and 時代 would need to be connected with の
I’m not sure what you meant to say by 本に理解しない. If you meant “do not understand (this) book” then この本を理解しない would be the right particle, but I feel like できない would be more natural than しない as well.