To complete the passage accurately, I'll suggest possible answers for the blanks based on the context provided:

1. For blank (1): A suitable option could be "while" or "as," indicating a simultaneous situation (e.g., "while the country’s independence was being taken away").

2. For blank (2): A good phrase might be "due to" or "because of," indicating the reason for the suffering (e.g., "the people were suffering greatly due to the harsh conditions imposed").

3. For blank (3): A correct word could be "such as," which introduces examples of the patriotic movements (e.g., "many patriotic movements, such as the Cần Vương").

With these suggestions, here is how the passage would read with the blanks filled:

"At the start of the 20th century, Vietnam was under the control of colonial rulers, **(1) while** the country’s independence was being taken away. The people were suffering greatly **(2) due to** the harsh conditions imposed by the colonial rulers. Many patriotic movements, **(3) such as** the Cần Vương movement and the Yên Thế..."

You can select the appropriate letters from your options for each blank accordingly.