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INVENTORIES
12 Months Ended
Dec. 31, 2019
INVENTORIES  
INVENTORIES

6. INVENTORIES

Inventories consist of the following:

 

 

 

 

 

 

 

 

 

December 31, 

 

    

2018

    

2019

Raw materials

 

$

3,821,620

 

$

12,965,337

Work-in-process

 

 

5,711,848

 

 

7,262,021

Finished goods

 

 

5,915,899

 

 

16,164,105

Total

 

$

15,449,367

 

$

36,391,463

 

Inventory write-down was nil,  nil and $326,598 for the years ended December 31, 2017, 2018 and 2019.