In the English Grammar Profile, A2 point 24 in the category of MODALITY is defined as:
adverbs in mid position or after main verb ‘be’, to modify an assertion, either through hedging or emphasis
A google definition of ‘assertion’;
noun = a confident and forceful statement of fact or belief.
For example:
I should probably start by looking at the bottom of the river.
*side note, ‘at the bottom of the‘ is the 8th most frequent 5-word Ngram in English.
iWeb 129,473
An iWeb search using the adverbs found in the EGP examples:
_V probably|definitely *
1 IS PROBABLY THE 101355
On the other hand, the lack of these qualities is probably the cause of many problems we have with other people.
PELIC STUDENT EXAMPLE: Thai, Male, Level 5, Writing class
2 WILL PROBABLY BE 60726
3 WOULD PROBABLY BE 47283
4 IS DEFINITELY A 44545
5 WILL DEFINITELY BE 39584
At first, you may think that it was not a good idea to take this class,
but soon you will definitely be sure that this is the class just for you.
Female, Level 4, Writing class
6 IS PROBABLY A 33147
7 IS PROBABLY NOT 25022
8 WOULD DEFINITELY RECOMMEND 24647
9 WAS PROBABLY THE 24136
10 IS DEFINITELY NOT 21479
11 IS DEFINITELY THE 20901
12 IS PROBABLY ONE 18246
13 WILL PROBABLY HAVE 16487
14 ARE PROBABLY THE 16400
15 WOULD PROBABLY HAVE 14392
16 ‘S PROBABLY A 14323
17 IS DEFINITELY ONE 13664
18 ‘S PROBABLY THE 13571
19 ‘S DEFINITELY A 13459
20 ‘S PROBABLY NOT 13218
21 IS DEFINITELY WORTH 12332
22 WAS DEFINITELY A 12153
23 ‘LL PROBABLY BE 12083
24 WILL PROBABLY NOT 11410
25 WAS PROBABLY A 11171
26 WOULD DEFINITELY BE 10002
27 SHOULD PROBABLY BE 8871
28 IS PROBABLY GOING 8781
29 IS PROBABLY MORE 8631
30 WILL PROBABLY NEED 8525
31 ‘S DEFINITELY NOT 8030
32 IS PROBABLY BEST 7773
33 ARE PROBABLY NOT 7716
34 IS PROBABLY WHY 7591
35 WILL PROBABLY NEVER 7556
36 WILL PROBABLY GET 7542
37 IS DEFINITELY AN 7377
38 ‘LL PROBABLY HAVE 7200
39 WILL DEFINITELY USE 6988
40 WOULD PROBABLY NOT 6735
41 IS DEFINITELY SOMETHING 6695
42 WILL PROBABLY WANT 6446
43 SHOULD DEFINITELY BE 6328
44 IS PROBABLY MY 6182
45 ‘LL DEFINITELY BE 6178
46 ARE DEFINITELY NOT 6001
47 WAS DEFINITELY THE 5934
48 ‘D PROBABLY BE 5878
49 ‘VE PROBABLY HEARD 5709
50 ‘LL PROBABLY WANT 5523
51 ARE PROBABLY A 5396
52 WILL PROBABLY TAKE 5383
53 ‘RE PROBABLY NOT 5251
54 ARE PROBABLY GOING 5187
55 WILL DEFINITELY HELP 4971
56 WILL PROBABLY FIND 4963
57 ‘S DEFINITELY WORTH 4867
58 ‘RE PROBABLY GOING 4833
59 WILL DEFINITELY MAKE 4810
60 CAN DEFINITELY BE 4753
61 IS PROBABLY BECAUSE 4658
62 ARE DEFINITELY A 4621
63 WAS DEFINITELY NOT 4564
64 WOULD DEFINITELY USE 4478
65 HAS PROBABLY BEEN 4415
66 ‘LL PROBABLY GET 4397
67 CAN PROBABLY GET 4379
68 CAN DEFINITELY SEE 4356
69 ARE PROBABLY MORE 4314
70 WILL DEFINITELY HAVE 4227
71 ‘S PROBABLY BEST 4197
72 ‘S PROBABLY BECAUSE 4186
73 IS PROBABLY BETTER 4184
74 WAS PROBABLY ONE 4149
75 IS PROBABLY WHAT 4110
76 IS DEFINITELY MORE 4081
77 IS PROBABLY DUE 4024
78 COULD PROBABLY BE 3994
79 IS PROBABLY JUST 3974
80 IS DEFINITELY GOING 3958
81 YOUVE PROBABLY HEARD 3957
82 WILL PROBABLY GO 3947
83 ‘LL PROBABLY NEED 3907
84 ‘S PROBABLY GOING 3896
85 HAVE PROBABLY BEEN 3887
86 COULD PROBABLY GET 3833
87 IS PROBABLY AN 3719
88 WAS PROBABLY NOT 3650
89 ‘LL PROBABLY FIND 3637
90 CAN PROBABLY BE 3599
91 WILL PROBABLY END 3577
92 IS DEFINITELY ON 3552
93 ‘VE PROBABLY SEEN 3542
94 WILL PROBABLY DO 3513
95 WILL DEFINITELY GET 3503
96 WILL PROBABLY MAKE 3491
97 WILL DEFINITELY RECOMMEND 3474
98 ARE DEFINITELY THE 3426
99 IS PROBABLY TOO 3315
100 HAS DEFINITELY BEEN 3247