In the English Grammar Profile, B1 point 63 in CLAUSES is defined as:
THE REASON WHY: defining relative clauses with ‘why’ after ‘reason’, to give an explanation and for focus.
*Note that “the reason that...” is B2.
A search in iWeb for:
the * reason why
1 THE MAIN REASON WHY 8371
2 THE ONLY REASON WHY 4692
3 THE REAL REASON WHY 1988
*The following student example is actually B2 grammar for adjectives of degree.
The real reason why people don’t take good care of their parents is that they are busy.
PELIC STUDENT: Arabic, Male, Level 4, Writing Class.
4 THE PRIMARY REASON WHY 1241
5 THE SAME REASON WHY 1231
6 THE BIGGEST REASON WHY 1024
7 THE VERY REASON WHY 846
8 THE EXACT REASON WHY 797
9 THE MAJOR REASON WHY 483
10 THE SECOND REASON WHY 454
11 THE OTHER REASON WHY 437
12 THE WHOLE REASON WHY 432
13 THE SOLE REASON WHY 357
14 THE MORE REASON WHY 315
15 THE FIRST REASON WHY 288
16 THE #1 REASON WHY 271
17 THE KEY REASON WHY 264
18 THE BIG REASON WHY 205
19 THE TRUE REASON WHY 172
20 THE PRINCIPAL REASON WHY 155
21 THE FUNDAMENTAL REASON WHY 152
22 THE UNDERLYING REASON WHY 142
23 THE CHIEF REASON WHY 125
24 THE ONE REASON WHY 117
25 THE BASIC REASON WHY 116
26 THE SIMPLE REASON WHY 116
27 THE TOP REASON WHY 112
28 THE CORE REASON WHY 101
29 THE PRECISE REASON WHY 98
30 THE ACTUAL REASON WHY 95
* * the reason why
1 THIS IS THE REASON WHY 7514
2 PART OF THE REASON WHY 5904
3 . THE REASON WHY 5785
I guess the reason why I like Japan the best out of all Asian countries is because I really feel close to Buddhism.
4 THAT IS THE REASON WHY 2385
5 THAT ‘S THE REASON WHY 1892
6 IS ALSO THE REASON WHY 1241
7 , AND THE REASON WHY 1135
8 WHICH IS THE REASON WHY 941
9 ” THE REASON WHY 774
10 MAY BE THE REASON WHY 749
11 I THINK THE REASON WHY 726
12 IT ‘S THE REASON WHY 624
13 COULD BE THE REASON WHY 609
NDTV.com14 IT IS THE REASON WHY 592
15 . AND THE REASON WHY 523
16 ? THE REASON WHY 512
17 AND IS THE REASON WHY 505
18 IS PROBABLY THE REASON WHY 468
19 MIGHT BE THE REASON WHY 460
20 ONE OF THE REASON WHY 409
21 THAT WAS THE REASON WHY 406
22 . THATS THE REASON WHY 392
23 ) . THE REASON WHY 359
24 THIS WAS THE REASON WHY 353
25 , BUT THE REASON WHY 347
26 IS EXACTLY THE REASON WHY 340
27 . ” THE REASON WHY 337
28 , IS THE REASON WHY 327
29 TO BE THE REASON WHY 308
30 ‘S ALSO THE REASON WHY 285
the reason why * *
1 THE REASON WHY IT IS 1304
2 THE REASON WHY I AM 988
3 THE REASON WHY I ‘M 976
4 THE REASON WHY SO MANY 952
5 THE REASON WHY THEY ARE 761
6 THE REASON WHY THIS IS 695
7 THE REASON WHY IT ‘S 686
8 THE REASON WHY WE HAVE 666
9 THE REASON WHY IS BECAUSE 646
10 THE REASON WHY I DO 634
11 THE REASON WHY I HAVE 632
12 THE REASON WHY WE ARE 616
13 THE REASON WHY . 606
14 THE REASON WHY YOU ARE 602
15 THE REASON WHY I DID 489
16 THE REASON WHY THERE IS 476
17 THE REASON WHY YOU SHOULD 456
18 THE REASON WHY THERE ARE 445
19 THE REASON WHY I WAS 443
20 THE REASON WHY IT WAS 436
21 THE REASON WHY IS THAT 430
22 THE REASON WHY I THINK 345
23 THE REASON WHY WE ‘RE 330
24 THE REASON WHY I SAY 326
25 THE REASON WHY HE WAS 325
26 THE REASON WHY WE DO 325
27 THE REASON WHY YOU HAVE 324
28 THE REASON WHY HE IS 301
29 THE REASON WHY I LOVE 293
30 THE REASON WHY YOU ‘RE 288
A2 Vocabulary:
could, exactly, might, probably, real, reason, should, simple, so, top, true, whole
*The following student example does not have the article before ‘reason why’.
There are two reasons why I like dogs.
PELIC STUDENT: Korean, Male, Level 3, Writing Class.
*The following example of the grammar is C2.
The main reason why it is so efficient is that it will make you more interested in reading or listening.