SN4 ""

No	Pattern	Freq
1	[adv] [verb] at the time	143
2	[adv] [verb] at the time	143
3	[adv] [verb] at the time	142
4	[adv] [vb pp] at the time	110
5	[adv] [vb past] at the time	14
6	widely [verb] at the time	10
7	actually [verb] at the time	8
8	well [verb] at the time	8
9	fully [verb] at the time	7
10	still [verb] at the time	7
11	[adv] [v-ing] at the time	7
12	[adv] investigated at the time	6
13	[adv] [vb infin] at the time	6
14	[adv] investigate at the time	6
15	often [verb] at the time	5
16	[adv] note at the time	5
17	already [verb] at the time	5
18	properly [verb] at the time	5
19	[adv] know at the time	5