General English Practice - English Learning Hub

Which of the following sentence is correct ?

A. I don't know why this happened

B. I don't know why did this happen

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Think of the answer — tap Show Answer.

Each card is tracked separately. Every card has its own score from 0 to 21. The ring under the question shows progress for this card only.
Each I Know = +1 point on that card. Tap I Know when you remembered the answer. The ring fills a little more.
14 points = Mastered. Tap I Know 14 times on the same card (not 14 different cards) and that card is mastered.
21 points = Expert. Keep going on the same card until 21 I Know taps — that is the highest level.
This Week & This Month count mastered cards — not every tap. Your goal bar moves +1 only when a card reaches 14 points (mastered) or you tap Already know. Example: 10 I Know taps on 10 different cards adds to your total Points, but This Week stays the same until you master at least one card.
Why isn't my bar moving? You are earning points on the ring, but the weekly/monthly bar waits until you finish a card (14 points or Already know).

Your goal: 0 / week and 0 / month means master that many cards — not that many random taps.

Quick example

You tap I Know on the card:

Points +1 — your total points go up (last card in the top row).
Ring fills — that card earns 1 point toward 14.
After 14 I Know taps on the same card, it is mastered — This Week / This Month +1.
After 21 I Know taps on the same card, it becomes Expert.
Already know — skip straight to Expert; counts as +1 for This Week / This Month.

Points — total earned across all cards. +1 on each I Know.

The ring — how well you know this card (0 to 21).

Week & Month — cards mastered toward your goal. 100% = target reached.

Badge	Points	What it means