I need help! I don’t know my Spanish that well

Pongo la carta dentro de uno de estos

Question 1 (fill-in-the-blank worth 1 points) fill the blank with the preterite tense of the verb in parentheses. yo a leer el libro ayer. (empezar) answer for blank 1: question 2 (fill-in-the-blank worth 1 points) fill the blank with the preterite tense of the verb in parentheses. ellos a trabajar. (empezar) answer for blank 1: question 3 (fill-in-the-blank worth 1 points) change this verb from the present tense to the preterite tense. yo empiezo answer for blank 1: question 4 (fill-in-the-blank worth 1 points) fill the blank with the preterite tense of the verb in parentheses. yo buena nota. (sacar) answer for blank 1: question 5 (fill-in-the-blank worth 1 points) change this verb from the present tense to the preterite tense. yo busco answer for blank 1:

Sheila conducts an investigation to see how the amount of salt dissolved in water affects the density of the water whichstatement best describes the correct plan for her procedure? the density and the amount of water are controls, and the amount of salt and the type of salt are variablesthe amount of water and the amount of salt are controls, and the type of salt and the density are variablesthe type of salt and the amount of water are controls, and the amount of salt and the density are variablesthe type of salt and the density of water are controls, and the amount of salt and the amount of water are variableso