Khi kết tinh dung dịch FeSO 4 , người ta sẽ thu được một tinh thể ở dạng ngậm nước. Công thức của tinh thể đó là

A.  FeSO 4 . 6 H 2 O

B.  FeSO 4 . 4 H 2 O

C.  FeSO 4 . 7 H 2 O

D.  FeSO 4 . 5 H 2 O

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

My mother is good at cooking. My father is bad at it.

A. My mother is good at cooking, but my father is bad at it.

B. My mother is good at cooking, for my father is bad at it.

C. My mother is good at cooking, or my father is bad at it.

D. My mother is good at cooking, so my father is bad at it.