How to get through one-block-high passages

http://www.gamefaqs.com/nes/525245-super-mario-bros-3/faqs/7459

WORLD 4

RED MUSHROOM HOUSE: Vends tanooki suits! Get one, they rule!

LEVEL 4-5: Later on, you'll see a brick in the sky. Bounce off the bullets to hit it. A vine will spawn. Do the same thing to get up to it and climb it. You get a tanooki suit! Hit the P-Block and follow the coins to safety.

WORLD 5

MUSHROOM HOUSE: Grab a tanooki suit now!

LEVEL 5-5: Whoever thought up this level should be shot! Go down the second pipe for a tanooki suit, but careful not to get any leaves or it goes to waste.

MUSHROOM HOUSE: If you're lucky, you get a tanooki suit.

WORLD 7

MUSHROOM HOUSE: This one is interesting. It only vends Tanooki suits, hammer suits, and frog suits. hehe.

FORTRESS: The fourth block on the top of that overhang is a P-Block. You can imagine what that does.... ;) However, it'll create a door which has a Tanooki suit ready for you. DO NOT get the fireflower or you're screwed. Time is of the essence on this level.

To make a Hammer Bros. turn into a coin ship:

1. Ensure there's a Hammer Bros. left on the world map
2. Start a level and finish with:
   1. A multiple of 11 coins (11, 22, 33, etc.)
   2. A score ending in 10 (2010, 3410, etc.)

Each second left on the clock gives you 50 points. That means you should end with an even number of seconds left on the clock if you have a score ending in 10. If you have a score ending in 60 you should finish with an odd number of seconds on the clock. Anything else and you're out of luck!

There are also white mushroom houses that appear if you get every coin on a particular level in each of the first 7 worlds:

1–4: 44 coins
2-2: 30 coins
3–8: 41 coins
4–2: 22 coins
5–5: 28 coins
6–7: 78 coins
7–2: 41 coins