$19.$ Chọn C.From the $8^{th}$ to the  $11^{th}$ day of the Third lunar month.
$\longrightarrow$ The Hung kinh temple takes place from the $8^{th}$ to the  $11^{th}$ day of the Third lunar month in Phu Tho.
$20.$ Chọn  C.Chung cakes,day cakes and five-fruit trays.
$\longrightarrow$ There is a ceremeny of offering incense and specialities such as chung cake,day cake and five-fruit trays to the Kings.
$21.$ Chọn A. They can join bamboo swings,lions dances,wrestling and xoan singing performances.
$\longrightarrow$ Morever,There are also many joyful activities including bamboo swings,lions dances,wrestling and xoan singing performances.

$\text{#HBA}$

19.C.from the 8th to the 11th day of the third lunar month

20.B.incense and specialities such as chung cakes,day cake and five-fruit trays

21.A.They can join bamboo swings,lion dances ,wrestling and xoan singing performance